I just checked the cel bounce that the other web site mentioned and I do that that. Another thing is that the spray pattern of the two injections isn't as umbrella perfect as I remember it being. I'm now wondering if I don't have a fuel problem. I'm off to check filters and pump out put.
Brake cleaner sucks for finding vacuum leaks! Use a propane soldering torch on high and you can direct to a very small area.
Surging is usually a vacuum leak. Other things that can do this on stock motor and tune is throttle blades to far closed. You can turn in throttle stop screw 1/4 turn and then start vehicle to rule this out. Do not do anything else with this screw, it does not set idle!
The hose going to air filter is air coming into engine, there should be another hose off TBI to PCV valve that sucks in air.
Your MAP sensor should be connected to tube in center/rear of TBI unit between fuel lines. Good stiff hose so it does not collaspe.
Post a picture or 2 of engine and conversion stuff and we can spot issues!
Your really going to need data so look into a cable from Robert.
http://www.gearhead-efi.com/Fuel-Inj...uy-ALDL-Cables!
TunerPro RT software is $39.
http://www.tunerpro.net/downloadApp.htm
ADX and XDF files for TunerPRo RT are free for all OBDI vehicles, your's are here:
http://www.gearhead-efi.com/Fuel-Inj...Information-42
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Fuel pressure is very important to EFI and the ECM has no way to know if it is wrong! Check fuel pressure!Originally Posted by Bart_3500
Also this is a conversion to older vehicle? Sometimes voltage is an issue, some old cars just don't have enough juice to keep good steady voltage at idle which ECM needs to run correctly.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
I'll try to run down the WTH so far. Vehicle is a '66 Ford Bronco with a 351 Windsor engine. I put the TBI on it about 5 years ago and it's worked great up until I decided to install a Centec wiring harness. Voltage is a good strong 14.8 running and close to 13 after sitting. This is all normal. Fuel pump pressure is 12/13 psi. I just (in the last hour) replaced both filters. One between tank and pump (mounted on frame close to fuel tank). And the other one is close to the engine, this is were I took the 12/13 psi reading. Again, it's been that way and ran fine for 5 years. This is not a normal surging, it's fucuating 1k to 1.5 K, that's a thousand rpm swing. Rick is to the point that it gets stuffy in the garage it's that RICH. I did get it to run up to 3 grand and it smoothed out. I held it there for a minute and then backed it down to 2 grand. Still smooth, as I tried to bring it back to idle it got rough again. I shut it off and checked the distributor and correct firing order. Distributor is tight so it didn't move. I think the spray pattern sucks Is the 12/13 psi enough?
You're in Limp Home Mode, the rapidly flashing CEL is indicating that. For some reason the EPROM is not being read.
The man who says something is impossible, is usually interrupted by the man doing it.
Well, I've about had it. I'm so discussed with this thing and I don't think the Rubicon trip will happen next week. I went to the wrecking yard and got two other ECMs one, has the same serial # as mine and the other one is missing the e-prom and it was rebuilt. I installed the matching one and it started and ran better but it's now back to the same as the first one. I did find a broken vac hose MAP sensor. It appears that after it chuggs long enough to go closed loop it runs pretty good above 1500 rpms. Below that it's missing and stumbling all over the place. The only code I get besides the12 now is a 43 code (knock sensor). Since I don't have one that makes sense. I did get from that John Wilson a computer cable but it's got a female terminal on it and it's the same as the lap top has (female also). To hook up a lap top I'll have to make a male to male connector to interface with it and then I "think" it'll be plugged into the A & B terminals. Correct me if I'm wrong.
After reading your post. When it goes into closed loop (after it warms up and runs above 1.5 K then I get a flash per second
Most of the yards don't guarantee the eprom is included. Since the same number ecm was used with 6 and 8 cylinder engines ranging from 4.3 to 7.4L it's up to you to transfer both chips to the replacement computer.
Is there a three or four letter code on one of the replacement ecms? Or are there marking that say it's for a particular engine? If you didn't use the small chip (called a netres) from the correct engine it will complicate your issues.
FWIW, I've been a tech for a long time... 26 years give or take a few small interruptions. Most of the time a problem like this can be traced to something that was changed or inadvertently done by the "mechanic." And a sharp eye is often all it takes to catch it. Getting the tools to see what the ecm is seeing can really save time though if you're stuck.
The MAP sensor issue will cause very poor driveability. Make sure the sensor is connected to a hose that has vacuum whenever the engine is running, not just when the throttle is open.
Some other quickie diagnostic steps: If there's a vacuum leak, the black IAC motor on the side of the throttle body will close as the ecm attempts to maintain desired idle speed. The IAC allows air to bypass the throttle blades and if air's being allowed in at another location, this passage will be redundant. You can listen for air entering the IAC passage while the engine is running. If there's a large, loud whistling or sucking sound coming from the IAC port that means the ecm is trying to increase idle speed, something that wouldn't happen with a vacuum leak. If there's almost no sound then you may very well have a leak as the valve is probably closed. a small to medium whistle-ish noise from the IAC then you've got normal or typical IAC flow and the problem is likely elsewhere.
Do you have a digital volt / ohm meter? You could check the O2 signal voltage while the engine is running to see if it indicates a rich condition. High volts = rich. You could also check TPS voltage with the throttle closed to see if it's acceptable. Same with coolant temp sensor. Check for 5V on the TPS sensor 5V line, too. Also make sure you've got a good, strong 12V supply at both injectors. Try using a test light on the 12V line to the injector while the engine is running. DO NOT connect the light to the ground side of the injector.
These might help narrow things down a bit.
I'm still stuck on this point?
Owning a EFI vehicle requires tools. A scantool or hanging around here use TunerPro RT software, your laptop and a cable, it will do what a scantool does but much more.
As 1project2many stated about the netres (small chip. Use the one from the ECM that ran, I would also use the big chip that ran. Disconnect power to clear codes and try again. If you get a flashing CEL then try the other chip. What are the four letters on it? We will see if it is at least a V8 Chip.
Hope we can get you going for the trip!
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
My orginal 7747 was marked AKDXI'm still stuck on this point?
Owning a EFI vehicle requires tools. A scantool or hanging around here use TunerPro RT software, your laptop and a cable, it will do what a scantool does but much more.
As 1project2many stated about the netres (small chip. Use the one from the ECM that ran, I would also use the big chip that ran. Disconnect power to clear codes and try again. If you get a flashing CEL then try the other chip. What are the four letters on it? We will see if it is at least a V8 Chip.
Hope we can get you going for the trip!
Okay, here's the info off the one 7747 AHWZ and 867361 M711891138
The other one rebuilt is 7-7747 and a DC code of 0609mn No other info.
Eaglemark for the last 5 years my pump has been working fine. I checked the pressure today and it's around 12 to 13 psi. What's it suppost to be?
I'm going to have to build a male to male connector. That John Wilson sent a female with two wires and prongs the computers I have also have female connectors installed. Two Leezes don't work around here. Gotta have two males in the middleRadio shack, here I come.
As for the trip I hope so too. Wife is very disappointed. Most wives don't want to go but mine can't wait. I'm going to take it over to a mechanic who's into Chevy's tomorrow. Times running out. I WILL LEARN MORE ABOUT THIS IN THE FUTURE. Thanks for all the help. It's 9 p.m. and Bronco is on the trailer for a 7 a.m. run to see him and hopefully figure out what I did without ending up owning my house.
AHWZ is a 5.7L auto so should work.
Fuel pressure 12-13 is good.
What the heck are you talking about with the John Wilson female male connectors? Got pictures?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Radio shack calls it a "D Sub connector". From John Wilson, I purchased two wires mated to one of these with small metal ends on the wires big enough to stick into the ALDL Link. Never been able to use it as the laptops have the very same female connector built into their computer cases.
I've slept and recovered enough to decide that I AM going on the Rubicon and will not disappoint my Bride and several friends. If I have to, I'll go back to a two barrel Ford carb., point distributor and very low pressure fuel pump. I'll pull this whole pos out of the Bronco, learn it, rewire it with correct wire colors and save it for my '70 Chevelle (300 hp 350 c.i 700R4). I did a complete conversion, putting a '90 Full size Bronco power train (351 complete with f.i. & over drive trans) and intergrating it with my 81 FSB normal electrical system. Difference is that I was using stock electrical equipment, not someone else's pos with ALL Red & Black wires going here and there with no prints/schmatic or rime or reasoning. It ran perfect the first time. Problem right now is that I'm up against the clock and didn't realize that the Centec wiring harness was for a later "early bronco" and things were in different places requiring a lot of soldering/double heat shrinking My '66 (first year of the Bronco) is different than all the reason of 'em. Wish me luck today or this afternoon I'll be going back to old school. Ford 2 barrel carbs are the only carb that's trail rated (pun intended)
Thanks for the info on the AHWZ. Any idea what the AKDX is?
Last edited by Bart_3500; 08-09-2013 at 03:21 PM.
To all who have tried to help and watched this thread
Up before 5 a.m., coffee made and I'll be out in my 2400 sq ft garage here getting the old school parts ready just in case the "spit" hits the face this morning. I know Chevelle will love giving up it's carb for a correctly built TBI system that "I" will (re)build. Now I need to learn how to modify 'em. This is a GREAT site with some equally good folks sharing their knowledge. I WILL learn and will share what I have learned with others who, in the future, will be as unknowledgeable as I am now. Learning is a wonderful thing
Being retired now I get up at the same time 4:30 ish and I'm out in my "man cave" (so it's been called) by 6 or 7. I usually work out there until 5,6 or 7 at night. Doing so, and leaving lunch and beer (to a minimum) I've dropped 29 pounds as of this morning. I will admit that I fell off the wagon yesterday and had 3 or 4 beers but it didn't hurt me any as I'd been out there more than 12 hours
Pretty sure you have an old serial connection. Laptops don't have them anymore and all new cables use USB plugs...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
That is horrible news!
Maybe you will read this and give it one more shot? So the harness you have is all red or black wires? Ouch that would be hard to track down but could easily be ohm each wire. There is also a voltage check list in the $42 info thread where you found wiring diagrams. It could be as simple as one power wire not connected or one ignition on wire not connected?
AKDX is a 4.3L auto chip, would probably run, not well but not as bad as you are now. Now if the small chip your using is a V6? That would be bad, still not sure if it would cause the LHM?
Your so close...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Wrong cyl count, on either or both PROM or NETRES cause rough running. I was reminded of this the other night when I swapped $58 in place of $59 and forgot to change the cylinder count of the bin I was using from 4 to 6 cyl.
The man who says something is impossible, is usually interrupted by the man doing it.
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