Help understadning my CJ7 SBC datalog

[Dlxman]

I have posted this under Unhappy CJ7, but would like to re-iterate my help needed. History - 70s 350 with TBI installed in 2014. .195 intake heads, 30 over pistons, mainly stock, but whole assembly balanced with TH400. Ran great, but now lacking power under acceleration. I got the Tunerpro so I can read more than a key turn for the OBDI. I attached a log file. Idled, went down the road with mild accelerations, WOT a couple times to feel/show the stutter. Idled at a turn, geared down and WOT through 1-3. Once home, I put it in park, and idle went through the roof!

Any help of what to look at, or try next, my wife and I would really appreciate it. We love driving this Jeep, but have not been able to enjoy it for most of the summer.

Diagnosing by wallet, and some manual reading diagnosis has not panned out. I'm savvy with engines, some electronics. New to the Tunerpro, I am asking for support! Moral support if any.

Thank you for your time!!

[dave w]

Is the data log for the 1227747 ECM?

dave w

[Dlxman]

Hi Dave, My apologies for not noting this. You are correct

[dave w]

Are the BPW and SA Hacks setup in the .bin file? ---- BPW and SA data are very useful.

Knock Accumulations are unusual. --- Maybe experiment with temporarily disabling knock? Monitors show a saw tooth, normally flat line with an occasional spike.

Mostly running rich. ---- Maybe an injector is dripping? Check injectors with a timing light to verify spray pattern.

dave w

[Dlxman]

I do not have the .bin file installed at this time. I only did the .adx so I can log some data. One thing I did not do was increase the latency in the USB to 1msec. Once I do this, I can re-log data (maybe it can smooth out the charts). I rebuilt the TBI, and did see a nice spray pattern about 1 month ago, but can check again. I am unfamiliar with the BPW and SA Hacks.

[tayto]

I have posted this under Unhappy CJ7, but would like to re-iterate my help needed. History - 70s 350 with TBI installed in 2014. .195 intake heads, 30 over pistons, mainly stock, but whole assembly balanced with TH400. Ran great, but now lacking power under acceleration. I got the Tunerpro so I can read more than a key turn for the OBDI. I attached a log file. Idled, went down the road with mild accelerations, WOT a couple times to feel/show the stutter. Idled at a turn, geared down and WOT through 1-3. Once home, I put it in park, and idle went through the roof!
if it ran good before and now doesn't it's time to go back to the basics, fuel delivery & spark. spark plugs, cap & rotor look good? what's your fuel pressure? have you verified your base timing? not saying scanning won't help but there are basics you should check especially if you haven't touched anything since you got it running 8 years ago.

on the note of "rebuilding the tbi". i don't like this term as it usually entails replacing a few orings and cleaning the unit. hardly a rebuild. did you check the throttle shaft for play? i haven't seen one in the last 10 years that couldn't use throttle shaft bushings. i recently am a BIG fan of taking the injectors to a professional shop that has an injector cleaner (ultrasonic) & test machine . getting a flow report is an excellent bonus as well. i don't guess at this stuff any more this is my recipe for a "rebuilt" TBI

[Dlxman]

Hi Tato, thank you for your input. All the basics have been checked as good or new. Cap and rotor were replaced last year with a bad connection to the ignition on module under the GM HEI cap. I have completed vacuum leak tests on all areas including the throttle shaft to end up clean! Which is good. As Steveo had mentioned, originally the injector spray pattern was good after the "cleaning and gasketing" of the TBI.
I checked it this evening, and behold the right (passenger side) put out no fuel. This was after warm up and closed loop. The left side had a cone, but seemed a little wet, not a fine(ish) mist. I did swap the RH to LH connectors to see if it was in the wireing, but no difference. Not sure if this was the right way or not. Regardless, I am going to pull the injectors and either clean or replace them.

I will let you know by this time next week if it was successful, as it will take time to get it done, and be abck in town to try it out.

[tayto]

good stuff! i just ran into this with a set of recently cleaned injectors. if injector is not spraying take a small hammer and tap the injector pod repeatedly while the engine is running. have brought 2 injectors back to life this way. i recommend finding a set of factory injectors and getting them cleaned, i have heard new injectors are made differently and can affect the tune/require further tuning

[Dlxman]

Hi Tato, thank you for your input. All the basics have been checked as good or new. Cap and rotor were replaced last year with a bad connection to the ignition module under the GM HEI cap. I have completed vacuum leak tests on all areas including the throttle shaft to end up clean! Which is good. As Steveo had mentioned, originally the injector spray pattern was good after the "cleaning and gasketing" of the TBI.
I checked it this evening, and behold the right (passenger side) put out no fuel. This was after warm up and closed loop. The left side had a cone, but seemed a little wet, not a fine(ish) mist. I did swap the RH to LH connectors to see if it was in the wireing, but no difference. Not sure if this was the right way or not. Regardless, I am going to pull the injectors and either clean or replace them.

I will let you know by this time next week if it was successful, as it will take time to get it done, and be back in town to try it out.

How do I know which injectors I have? No markings....??? TBI #17089018 3459 JWZ

[tayto]

that # appears to be the number stamped on the TBI unit itself. if the injectors have no number etched in the top or paint markings the only way to determine what they are is to get them flow tested @ 13 or 14 psi

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?81-GM-Injector-size-color-and-part-numbers

[dave w]

Perhaps a picture of the EXTREMELY UNUSUAL Knock (sawtooth pattern) will be helpful?

dave w

16999

[dave w]

Perhaps a picture of the EXTREMELY UNUSUAL Knock Accumulation will be helpful?

dave w

17000

[tayto]

i would focus on the injector that's not firing personally. 4 cylinders not firing might be what knock sensor is detecting.

[Dlxman]

Hello All, I have had the injectors ultrasonically cleaned and replaced. Still runs poorly after warm-up. The data log from 8/26 is attached. I also have no idea why the sawtooth pattern exists. Could this be a bad ground?
Checking the spray pattern with a timing light (cyl 1), I could only see the one injector spraying (again), but do both injectors fire simultaneously, or do they alternate? I could see fuel hitting the port of the throttlebody on the injector that appears not to be firing.
I have two new matched injectors on the way, but wont ship until after Sept 1.

Thank you once again for your support and suggestions. I'm not one to give up or afraid of hard work!!

[dave w]

I have only looked at the first data log posted in this thread. It seems odd to me the engine would be running rich with only one injector working.

Perhaps a quick timing light test of unplugging one injector at a time would be a worthwhile experiment?
Ignition key off ... unplug one injector ... start the engine and check spray pattern with timing light ... repeat test on other injector.

Seems one of the logical outcomes of the above test might be . . . if one injector is not working ... the engine won't start?

Sawtooth knock pattern, possibly measure the resistance of the knock sensor. Remove the electrical connector from the knock sensor and measure from where the were the electrical connector was plugged into (center of knock sensor) to ground.

dave w

[tayto]

you should see them both firing. sounds like 1 still isn't firing. did you try my tapping trick on the injector housing while the engine is running? swap the injector connectors and see if the "working" injector is still firing. could possibly be a connection at injector or ECM, or the ECM itself (failed driver). it's possible 1 injector is bad even though they cleaned them.

[Dlxman]

I did try tapping the injector housing as suggested, and also originally swapped the connectors as noted in a previous reply. Neither one produced gas out of one injector. The new matched injectors ship Sept 1, so hopefully I can get the by Friday. I did replace the ECM through original diagnosis by the manuals. This did not change anything, so I now put the old ECM (6 years old) back in. Hoping it is the injector.

Also, commenting on Dave's post, I do not have a knock sensor. The *.adx file I got from the sight had it in there, so I am going to remove that and a few things I do not have. this should clean up the data log a bit.

[tayto]

just to cover your bases have you checked for continuity in the injector wires back to the ecm and also to ground?

EDIT: nm you already confirmed swapping the injector plugs which tell me wire integrity and ecm are OK

[Dlxman]

Hi Tayto, great idea nonetheless to check for continuity. No harm, no foul!!

[Dlxman]

AAARRGH, as C. Brown would say when trying to kick the football.
New injectors, still one firing. Maybe I was mistaken when I swapped the connectors to the injectors previously. I am starting to question myself.
In the manual Chart A4 "Injector Circuit Diagnosis All Engines". It states to disconnect the distributor 4-way connector and check with a test light for blinking during ignition on.
I am unable to locate such a connector, and if it is the ignition module, I have two connectors with two terminals on each side. I have narrowed it down to looking for the Lt Blu circuit 467, and how to see if I am getting juice to it. My initial thought is to go from the connector about 1' and scrape a bit of insulation off for a quick continuity check at the connector level.
Another question to check the same circuit at D16 on the ECM, is this the connection that plugs directly into the ECM?

Thank you so much for your patience and help.

[Dlxman]

Hi Tayto,
New injectors, still one firing. Maybe I was mistaken when I swapped the connectors to the injectors previously. I am starting to question myself.
In the manual Chart A4 "Injector Circuit Diagnosis All Engines". It states to disconnect the distributor 4-way connector and check with a test light for blinking during ignition on.
I am unable to locate such a connector, and if it is the ignition module, I have two connectors with two terminals on each side. I have narrowed it down to looking for the Lt Blu circuit 467, and how to see if I am getting juice to it. My initial thought is to go from the connector about 1' for a quick continuity check at the connector level.
Another question to check the same circuit at D16 on the ECM, is this the connection that plugs directly into the ECM?

Thank you so much for your patience and help.

[tayto]

i believe one side is constant key on voltage (RED & WHT) and the other side is on pulsed ground by the ecm (BLUE & GREEN)

[Dlxman]

I have to check the colors you note for sure. The continuity for both injector circuits to ECM are good. I will check for resistance for both next. Looking at the ignition control module as mentioned. The manual states to check for a reference pulse to ckt 430 (ppl/wht) with ignition on. My ignition module is most likely pre 1990 and only has the two pins per side i.e. a 4 pin ICM. Do you know which wire would supply the reference pulse of the colors you noted? I am unable to find the ppl/wht ckt 430 going to my distributor.

[tayto]

did you try swapping the injector connectors? does the problem move with the connector or stay on the same side?

[dave w]

Picture of a 7 Pin Ignition Module, common for OBD1 EFI System.

dave w

17056

[Dlxman]

I did, and the problem moves with the connector. Meaning injector is good, signal to the other bad.

[Dlxman]

Thank you Dave, this is what I am looking for. Is this in the 89 or 90 emissions/fuel manual? I only have the B, C and G, W posts on my ICM.17057

[dave w]

Thank you Dave, this is what I am looking for. Is this in the 89 or 90 emissions/fuel manual? I only have the B, C and G, W posts on my ICM.17057

Using the 4 pin module works for a "Fuel Only" TBI system, meaning no spark control from the ECM.

Likely, if one injector is working, the 4 Pin Ignition Control Module is working fine.

The ECM has two injector drivers, maybe one of the injector drivers is bad?

dave w

[Dlxman]

Thank you, I was hoping the Ignition Control Module was bad. 3 months ago, I removed it and had it tested at a parts store and it was fine. I also heard that it could be bad and still test fine... (word on the street). I would like to test the circuit as noted in the manuals, but I would only guess which wire is sending the reference pulse. How, or where would I check for an "injector driver"?

[Dlxman]

BTW, I also believe this is a "fuel only" TBI now that you mention it. This is also a Howell TBI If I have not noted so earlier.

Thank you so much for your time. I have a new ignition control module to add to my parts list.....unfortunately.

[Dlxman]

Using the 4 pin module works for a "Fuel Only" TBI system, meaning no spark control from the ECM.

Likely, if one injector is working, the 4 Pin Ignition Control Module is working fine.

The ECM has two injector drivers, maybe one of the injector drivers is bad?

dave w

I also replaced the ECM, if the "driver" is a software driver, and had the same issue. Since then, I put the old ECM in since apparently it was okay (since no change, now I have two ECM's ... good or bad I do not know. Too much diagnosis by wallet, I desired to go a bit more high tech and found this forum. I am really thankful for all the support, and am now over my head. I am an engineer, so can handle a bit of technology.
The steering column was removed, and harness from the ECM was inspected as OK. Continuity checks proved good. All the grounds are new, as well as the frame. Using a test light to D16 and D14 proved I had a light at D16, but not D14 with ignition on.... Hmmmm. This led me to an open circuit on on 468 LT GRN (which was included in the steering column drop and pulling the ECM connectors out for inspection. Again. No issues, breaks, bends.. Going to Injector circuit diagnosis, I can not tell with the system I have if I am getting a reference pulse from the ECM.

[dave w]

The injectors are powered by the ignition switch, both "On" and "Start" positions. The computer Pulses Ground (measured in milliseconds) to the injectors. The more milliseconds ground is sent to the injectors, the more fuel to spray out of the injectors. So 25 milliseconds of ground will spray more fuel than 15 milliseconds of ground.

Schematic below is 1989 TBI, other years are very similar or identical to the 1989 schematic.

dave w



17058

[tayto]

which injector IS working the one at D16/BLU (injector 1) or D14/LT GRN (Injector 2)?

ALSO, i think it's time to ditch the test light. Do you have a DMM? I like to see what the actual voltage is. Even using continuity tester on DMM will register up to 50 ohms which can be a large voltage drop...

[Dlxman]

which injector IS working the one at D16/BLU (injector 1) or D14/LT GRN (Injector 2)?

ALSO, i think it's time to ditch the test light. Do you have a DMM? I like to see what the actual voltage is. Even using continuity tester on DMM will register up to 50 ohms which can be a large voltage drop...

Hi Tayto, The injector D16/Blu is functional. I do have a DMM and can check the voltage. The reason for the test light was per the manuals as a quick test to check for power to ground and rule out a circuit issue, if yes >>> if no>>>.
Do you desire that I check the voltage at each connector with "key on", "Cranking", both?

[Dlxman]

Thank you for clearing some of this up. I apologize, however I still have some questions concerning this. So with the initial "key on", I should be able to have a DMM on the ground side of the ignition control module to see a pulse? I am trying to find the circuit from the ECM to the ignition control module to validate that circuit. I had thought it would be the ECM B5 ppl/wht ckt 430, but cannot locate that to my distributor.
Perhaps there is something else I should be checking.....

[tayto]

so with your DMM referenced to ground, negative lead on battery or chassis, you want to see if you have 12+ volts on the WHITE and RED wires with key on. you can then check continuity to ground on the BLUE and GREEN wires. with the engine NOT running you should have no continuity to ground. should only have pulsed ground when the engine is running if my thinking is correct. you can then check the ground with engine running and see what its doing. i am wondering if you have a poor connection at the injector or a bad #2 injector driver in ECM if all the wires rang out OK... keep us posted

EDIT; not sure how Howell has setup your system, if the 430 wire isnt there and ran before i would expect it to not be the problem.

EDIT 2: I SWARE i've seen each injector fused separately by GM in the past but i may be remembering wrong, i assume Howell has an auxiliary fuse block and you've verified all the fuses are good there?

[tayto]

this is the test light gm is referring to. also called a noid light

https://m.media-amazon.com/images/I/61zHm0gvMrL.jpg

[Dlxman]

so with your DMM referenced to ground, negative lead on battery or chassis, you want to see if you have 12+ volts on the WHITE and RED wires with key on. you can then check continuity to ground on the BLUE and GREEN wires. with the engine NOT running you should have no continuity to ground. should only have pulsed ground when the engine is running if my thinking is correct. you can then check the ground with engine running and see what its doing. i am wondering if you have a poor connection at the injector or a bad #2 injector driver in ECM if all the wires rang out OK... keep us posted

EDIT; not sure how Howell has setup your system, if the 430 wire isnt there and ran before i would expect it to not be the problem.

EDIT 2: I SWARE i've seen each injector fused separately by GM in the past but i may be remembering wrong, i assume Howell has an auxiliary fuse block and you've verified all the fuses are good there?

Only to clarify, I do have a color deficiency, so I call for support to find the correct colored wire. Sometimes it takes me a bit. I have two pics, one of the distributor and one of the harness replacement for the plugins to the distributor.
I got twelve volts at each wire on the B & C (brown? & red?) side of the Ign Ctrl Mod. 0V at the green and white shown. I have 12V at each injector connector. Started and the opposite injector is firing (lt grn). I know you say no way. I put tape on the connector that was good to not get confused. I am going to check or tighten each injector connector terminals.

I agree to give up on the ckt 430. Yes, there is a separate fuse box near the ECM, and various other fuses that all check OK.

I'm also going to start it and fuss with the connector wires push/pull to see if I get juice while running...

[tayto]

looks like an "old school" gm big cap HEI to me... not familiar with how Howell does these setups. they must be picking up a distributor reference somewhere to fire the injectors? any wiring diagrams or literature supplied when you got it?

[Dlxman]

The howell system uses the tach lead off the distributor to signal the ECM to fire.

Update.. The injectors do not fire simultaneously. Using the timing light on number one, I could only see one cone, and the other a bit of a mist. I did a slo-mo video being back lit and could see a good cone out of both injectors. perhaps one injector is 180 deg apart. I fussed with the connectors, pulled out the lead of the connector and checked for fit, voltage, continuity... put it together and they both fired.

Ran awful one day, pulled the tack wire, and with key on, momentarily touched 12v to the wire, and both injectors fired.. Put the connectors back on, air cleaner etc. Went down the road just fine with all sorts of power. no misses, stumbling..

I have not found any reason why the stumbling occurred, nor why it is gone today. It may come back on a longer trip, which has happened in the past.

I have attached the log file from this trip, along with some spray cone back lit pics. The videos are nice, but at 55 to 100mB, I feel they are too big to post.

I am curious why my 02 sensor is bouncing up and down eratically. Is the ECM still learning? Is this normal? Seems to smooth out at WOT.

[tayto]

normal the o2 voltage is changing like that @ idle/light cruise. i have a feeling you've fixed the problem during this process. i normally would reset the ecu by disconnecting the battery after a repair like this. i have had an ecu "learn" to run poorly and after you repair something it still doesn't run right until a reset. it's also not uncommon for the ecu to need a few days or even weeks of driving to "settle in". Again I have no idea how close Howell got the tune, but I would think it is pretty generic. Glad it's running hopefully problem does not come back.

EDIT: was distributor new or rebuilt when did this swap?

[Dlxman]

I sure hope the problem is corrected. We will see if it randomly pops up as it had in the past. I did have the battery disconnected while messing with the wiring and ECU, so thank you for this tip. I also agree to let it drive for awhile to have it learn more (hopefully learn to behave!!). If the problem does come back, I will know what to look for. This post and website has been a tremendous wealth of information and help. I sure do thank you for your time, efforts and patience with me through this problem.

BTW, I am not sure if the distributor was new, or rebuilt in 2014 I'm thinking new. I have my old points dist, original 69 QJ, and 69 cast iron intake as a back up (too many times I thought about reverting).
Thanks again.

[tayto]

in my experience, i have always had no run issues with distributors. have also seen where a vehicle will run for awhile then shut off and not restart until cold. I recently got a reman'd distributor for a 92 GMC from Autoline. I had my own GM performance distributor in there so the vehicle was drives le. When I swapped it, it ran like crap and even my timing light was doing weird things. I messed around with it for over a hour before deciding to throw my distributor back in and truck ran good again. I tried replacing the module with a GM one i had and the reman dist still ran bad, so thinking maybe the wrong pickup coil was installed? I guess what I am saying is maybe it's worth replacing the dist with a known good one next time. GM HEI's are generally solid so no need to reinvent the wheel.

[Dlxman]

It ran well on Sept 20th. Granted it was only briefly. A couple days later, not changing or adjusting anything, a longer drive resulted in worsening performance. The next day, on a longer trip, same thing. Returning home, after a longer ride, I decided to log a run.

I THINK I FOUND THE SMOKING GUN.

I attached 4 files, two datalog files, and 2 excel (open office *.ods) files. The 920 is when the jeep ran WELL, the 926 the jeep ran POOR.

Looking at the excel files, I organized the data as I needed to see it. I saw the column for the ALDL enabling. On the running well file, the ALDL was enabled. On the POOR running file the ALDL was disabled. Plus all sorts of wierd numbers up and down...

So, if the smoking gun is the enabling of the ALDL, then I need to trace down where the short is to turn this on and off. I suspect ignition to ECM somewhere.

Would you think that an ALDL not enabled would perform this way? Gas only TBI...

BTW, I do have an oversized Novak Jeep radiator which keeps it running cool if that may be a problem of the engine never getting warm enough... just a thought...??...

[tayto]

i'm pretty sure ALDL mode when there is a 10k resistor between terminals A & B on the ALDL connector. Not sure what datalogging cable you are using but my Moates one has a switch to toggle resistor or no resistor.

you can take your meter and measure the resistance on your datalog cable between pins A & B

[Dlxman]

I also have the Moates ALDU1 & cable1. I believe Moates state that with my "older" setup that I can only use the 10k resistor. The other switch is for newer speed density reading.

So having the ALDL enabled, or disabled does not affect how it runs?

[dave w]

Maybe converting to computer controlled timing with a distributor like the one in the picture below is an option? Requires adding four wires to the harness.

https://www.ebay.com/itm/164895931058

dave w

17143

[mecanicus]

"BTW, I do have an oversized Novak Jeep radiator which keeps it running cool if that may be a problem of the engine never getting warm enough... just a thought...??... "

Check your thermostat, it should keep the engine temperature at the right level.Only then the engine will work right. Just an idea.

[Dlxman]

Thank you for the update. This may all lead to replacing the distributor. It is hard for me to understand why it would run great one day, then not the next. Timing, Temp, aside. One day 9/20 running well. Next day 9/26 running poor with no adjustment in between. The original question I have is if the ALDL shows Disabled, will this affect the performance?

This setup ran great for 5 years, until early this summer. 180 deg Thermostat was replaced also this summer.

Thank you all for your help! It is very much appreciated.

[Dlxman]

I'm not getting anywhere on finding the root cause. I hooked up the Moates datalogger and Tunerpro RT5 prior to getting on the highway after warm up. The most recent datalog and odf (excel) file is attached from the run. Still getting lag under power, sounds like a miss, but idles fine. The engine seems to run rich under acceleration. All sensors replaced, and no error codes. 11 psi under all conditions idle through WOT. I noticed, I only could get 60% from the TPS at WOT (80mph in a jeep with oversized tires is scary!!). If anyone with the same kind of condition, or symptoms can see something I do not, ANY information would be appreciated.