high map on hwy

[PJG1173]

Ok, so just when I thought things were going good I took my truck out on the HWY 17 bypass (all 3 miles of it we have) where I could safely get up to 65 - 75 without hitting a stoplight. there are several bridges and overpasses so I though that would be a good place to get some logs. needless to say I never got that fast. at about 60ish MPH in 4th in TC lockup 1900 RPM map was at 95+ kpa. I had to keep the trottle at 50% to maintain 65 MPH any more and I would have been in PE. what gives? do I need more/less timing? attached is a copy of my logfile and the adx file i'm using. If someone could look at it and point me in a direction that would be helpful.

[EagleMark]

Something is wrong that's for sure, I'll try to find some time to look at your log today but tell us which vehicle, and specs.

[PJG1173]

this is on my 93 chevy s10 ex cab
4.56 gears
36x12.5x15 TSL's
01 4.3 block bored .030
9.8:1 compression
edelbrock 2114 dual plane vortec intake
transdapt tbi adapter
61lb injectors @ 13psi
adjustable FP regulator
TBI with ultimate tbi mods
ported and polished vortec heads
back cut valves
comp cams 266hr
1.52 roller tip rockers
hedman long tube headers
kwik-cat racing cat
cold air intake
built 4l60e
2075 stall converter
Crane HI6 CDI ignition

[EagleMark]

That thing should run better than that!

Your open loop the entire time so I'm guessing your tuning VE by the wide band. WB AFR are in the ball park. Spark advance is a little low, especially at idle around 14 degrees and 650 RPM with a slight fluctuation of MAP. I would raise the RPM up to 750 or so, set base timing at 10 degrees? Also set base timing in chip from 0 to 10 and see if that fluctuation goes away. If not look for a vacuum leak.

Are you using the Narrow Band simulator? Your O2 readings and cross counts are weird?

I can see where your trying to cruise at 60ish MPH and MAP is 95ish with steady state TPS. Narrow band reading is way lean. WB is close. One thing that stands out is WB AFR is fluctuating, this may be a cylinder misfire or miss, I would check actual timing with a light on balancer and see if data log spark is showing same as timing light. Also pull plugs and read them to see if one is off. If one has a miss or one cylinder is picking up a vacuum leak it will throw everything out of wack...

[PJG1173]

Base timing is set to 6* and properly reflected in the bin and adx. Idle timing is 20* verified with a dial back timing light. I've looked for a vac leak but might be something that only leaks while under a load. The NB is the factory one when i was simulating the reading was more stable. at anything below 50 mph cruising this is great. WOT is on point pe 12.8 ish through the rpm's. just seems like this thing can't hack rolling down the hwy at 60 - 65. I wish I would have better datalogged this thing when it was stock. :mad1:

[EagleMark]

Timing I saw in log at idle was only 14? So we're losing 6 degrees somewhere? Since you have a dial back timing light see where timing is at higher rpm, in the data log there was a lot of 24ish degrees around 2400 RPM. The fluctuating WB AFR reading still seems to indicate a miss fire, at this point reading plugs would still be a good idea

I'm not familiar with the Crane HI6 CDI ignition at all?

Vortec heads have a very different spark plug?

Vacuum leaks are much more prevalent at idle when vacuum is higher then say 95 MAP when there is no vacuum... I have found vacuum leaks with short bursts of starting fluid when brake clean and carb clean have failed. Please be very careful using SHORT bursts of starting fluid as it is very flammable. Another approach is a propane soldering torch unlit wide open pointed at anywhere they could be vacuum and listen for rise in idle.

But I don't think that is your issue at 60 MPH at 95 MAP 40%+ TPS is just dead on power? Do you have a thick vacuum hose that won't collapse hooked to MAP from center vacuum port on rear of TBI between fuel lines? I did see AFR go to 10 when decelerating at one point then climbed back up to 17.9 before it became stable again?

Just going over some basics here, I don't know if they will help maybe someone else can see something I missed?

[EagleMark]

Here's your 6 degrees missing in adx, it is a note in the spark advance value "Change last number(offset) to initial advance of engine, for correct display."

Last number offset in conversion is 0.00000 and you have 6 degrees so it should be 6.00000

[PJG1173]

I'm replaying the log right now and I don't see 14* at idle the lowest I'm showing with the idle flag on is 16.5 and thats only a couple hits. I've used the timing light several times to verify timing and it has been spot on every time. I just changed the spark plugs a couple weeks ago and they all looked the same. Nothing real notable. the vac line going to the MAP sensor is plastic with rubber boots at each end. I've checked it for kinks and cracks. above 60mph throttle is unresponsive to say the least. I figured afr dropping when I let off the throttle is DE not being tuned yet IDK.

[PJG1173]

Here's your 6 degrees missing in adx, it is a note in the spark advance value "Change last number(offset) to initial advance of engine, for correct display."

Last number offset in conversion is 0.00000 and you have 6 degrees so it should be 6.00000

yes thats what is in my adx file. should be in the one I posted.

[EagleMark]

My bad I was using mine...

Sure is dead looking on power up there?

What does your BLMs look like in closed loop? Wondering if your wide band is off? Calibrated to free air? Ground to engine block?

[gregs78cam]

Just as a test, you might try bypassing the Crane Ignition module. I tried running the Camaro with my Mallory Digital 6, and it really didn't like something about the spark. To I just bypassed it until I can do further testing.

[PJG1173]

Just as a test, you might try bypassing the Crane Ignition module. I tried running the Camaro with my Mallory Digital 6, and it really didn't like something about the spark. To I just bypassed it until I can do further testing.

if the weather is nice enough tomorrow I'll bypass it and see what happens.


My bad I was using mine...

Sure is dead looking on power up there?

What does your BLMs look like in closed loop? Wondering if your wide band is off? Calibrated to free air? Ground to engine block?

I haven't tried putting it in CL in months so couldn't tell you. I'll try that tomorrow. I calibrated the WB to free air a couple weeks ago and it is grounded to the same wire comming in from the block to the pcm. the funny thing is this only happens on the hwy. It runs pretty good any other time. just running around town its fine, good throttle response, takeoff power, dosent struggle to get up to speed. I know its about arodynamic as an umbella at those speeds and trying to turn 75lb a piece tires will put a load on it. I just dont understand. maybe its just a v6 thing.

[EagleMark]

if the weather is nice enough tomorrow I'll bypass it and see what happens.



I haven't tried putting it in CL in months so couldn't tell you. I'll try that tomorrow. I calibrated the WB to free air a couple weeks ago and it is grounded to the same wire comming in from the block to the pcm. the funny thing is this only happens on the hwy. It runs pretty good any other time. just running around town its fine, good throttle response, takeoff power, dosent struggle to get up to speed. I know its about arodynamic as an umbella at those speeds and trying to turn 75lb a piece tires will put a load on it. I just dont understand. maybe its just a v6 thing.I don't think so? 36 inch tires and 4:56 gears and that much work done on motor, cam is 1400 to 5400 RPM so your in the power range... should really do better. Inline six jeeps do fine with that tire and gear on stock motors.

[PJG1173]

I don't think so? 36 inch tires and 4:56 gears and that much work done on motor, cam is 1400 to 5400 RPM so your in the power range... should really do better. Inline six jeeps do fine with that tire and gear on stock motors.

actually the operating range is 1800 - 5000 (http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=575&sb=0) cruising at 60-60 is right there at the bottom of that. running the 1.52's increased my duration a hair I suppose and I know I lost some low lift velosity from the port job. I know this thing pulls well over 5k and doesn't run out of breath. this just has me stumped. I might give the tb adapter a shot of propane and see if it really is leaking. I shot it with carb cleaner last weekend and it didn't indicate it was.

could this be timing related?

[EagleMark]

Hmmm? Seems like differant sites have differant specs for that cam, probably same grind has higher low end RPM range in 4.3 then one I looked at was 5.7 on eBay... did you degree that cam when installed?

Sure could be timing related! We will know when you go without that crane box, but then you've checked timing? I'd like to see that swinging WB AFR go away... I'm kinda lost. We did have a thread here about a 5.7L vortec head swap and found a export 5.7L TBI bin and timing tables were completly differant. Have you compared them to what you have? It looks like a 9.8 degree bias on top of your off throttle timing table IIRC...

Since your doing some testing tomorrow you could add some timing in that range and see if it starts to put out some power? Or if you had a set of smaller tires like 33s would get some more RPM and see if it comes to life?

[PJG1173]

for the timing table I copied the table from a 98 s10 4.3 with an efilive eval. it took bumping up the timing considerable amount to get the motor to come alive and get to this point. I'm going through some of my old datalogs from before the CDI install to see if there is an hints of high MAP around that speed. I didn't really pay attention to it since I was more working on cruise in town. Yes the cam was degreed when it was installed. I had it in 4lo a couple nights ago doing some hole shots in the mud when I went to pull another truck out. all the guys out there could say was OMG thats a v6?, so yes it comes to life with more rpm.

[PJG1173]

ok so after a busy afternoon messing with the truck I am no futher than where I was before. I bypassed the crane CDI which didn't do anything for me. sprayed everything semi flamable and propane at the tb base and adapter no vac leaks. I played with the timing adding 3* in the high map around 1600 - 2000 and there was no change still 95 - 100 kpa at 60mph. I loaded a CPI timing table which was similar to my modified vortec table and still no change. I then copied the stock spark table and it struggled at 50. I put a 4 wire NB O2 in with the ground attached to the block. no change there either still reading the same as the old one. without knowing if the knock sensors are working I am a little reluctant to advance the timing any more than I have.

[RobertISaar]

you know... maybe you've just lost that much lower RPM torque?

[PJG1173]

thats what I'm starting to think. I'm sure if it was sitting at stock height with stock gears and tires this wouldn't be an issue.

[EagleMark]

5:13 gears?

[gregs78cam]

Ok, let me get this right.....95-100Kpa, 2000rpm, and 60mph. At that MAP, you are essentially WOT, just without TPS showing it. If you do go WOT does it accelerate through that spot with the addition of PE?

266HR should give you plenty of torque for that truck. 4.56s with 36s should not make a big difference in final drive ratio from stock.

[PJG1173]

yes if I go WOT it will accelerate to 80 - 85 no problem.

[EagleMark]

Ok, let me get this right.....95-100Kpa, 2000rpm, and 60mph. At that MAP, you are essentially WOT, just without TPS showing it. If you do go WOT does it accelerate through that spot with the addition of PE?

266HR should give you plenty of torque for that truck. 4.56s with 36s should not make a big difference in final drive ratio from stock.That's what I thought too. When I searched real quick RPM was 1400 up but he said on a 4.3L it's 1800 up, he's right at 1800ish...

So if you got passed that point to 80 MPH does it have power and same vacuum?

You could always degree that cam... ahead right for lower RPM? I always get that mixed up...

Greg did you see his data log at that speed? His WBO2 was swinging about 1 AFR, shouldn't it be more steady? He was running open loop. Now that I think about it was 14 to 15ish, I wonder if he got it down a little would help?

[RobertISaar]

open loop and swinging are generally a bad combo. :laugh:

and yes Mark, advance the cam to shift the powerband lower, or at least that's the way i remember it.

[EagleMark]

open loop and swinging are generally a bad combo. :laugh:
Wouldn't that be a missfire? Or?

[gregs78cam]

Can you tell us your air intake setup? Just like stock? or modified? how so?

[RobertISaar]

hmm.. possibly. assuming the VE was done correctly and the VE swing wasn't caused by AE/DE, then yes, i would look for a soft misfire.

[EagleMark]

At steady TPS 1900ish RPM 90ish MAP 60 MPH no AE or PE and WB AFR swings about 13.9 to 14.9ish? Never steady?

[PJG1173]

Can you tell us your air intake setup? Just like stock? or modified? how so?

I have a edelbrock 2114 vortec intake. with a mr gasket squarebore to speadbore adapter and a transdapt tbi adapter. I have an airaid CAI from the tb to the front driver fender. filter is segregated from the engine compartment by a box.

[PJG1173]

hmm.. possibly. assuming the VE was done correctly and the VE swing wasn't caused by AE/DE, then yes, i would look for a soft misfire.

not familiar with a soft misfire. what would cause this?

[PJG1173]

At steady TPS 1900ish RPM 90ish MAP 60 MPH no AE or PE and WB AFR swings about 13.9 to 14.9ish? Never steady?

I don't think I've ever seen the wb steady. I could slow down the sample rate that may calm it down some.

[EagleMark]

Soft miss fire I believe is same as a lean misfire in the sense it is firing but not combustion fuel properly. Lean misfire is just fuel mixture to lean to light off, or light and not burn completely.

It's possible, we are kind of breaking new ground here of things experienced dyno guys don't like to talk about, at least around here. If you read these statements below from my LC-1 WB it says it could be to fast and slower will be a better average. But then again it says it can measure individual pockets of gas... which might be where it's at now and showing one cylinder off? With TBI or a carb in a wet intake manifold the mixture is not going to be same in every cylinder like dry intake manifold MPFI.
The normal state of the analog outputs is to update the outputs every time the LC-1 takes a new measurement. The LC-1 is fast enough to distinguish individual pockets of exhaust gas. For many applications this will be too fast. The advanced programming allows to set the analog out update speed.
When setting the LC-1 to the slower response speed settings the measured mixture data will be averaged over the response time setting before being output.1) An exhaust leak will allow oxygen to enter the exhaust stream and therefore will measure leaner than the engine is actually running. For correct measurement, airleaks in the exhaust MUST be prevented under all circumstances.2) Missing ignitions (where the air-fuel mixture does not ignite) also pump unburned oxygen into the exhaust and cause the LC-1 to measure lean.

[gregs78cam]

I have a edelbrock 2114 vortec intake. with a mr gasket squarebore to speadbore adapter and a transdapt tbi adapter. I have an airaid CAI from the tb to the front driver fender. filter is segregated from the engine compartment by a box.

Ok. I was thinking that maybe you were having a situation where airflow past the intake opening was generating additional vacuum in the intake tract. Similar to how carbs sticking out of a hood can have fuel issues with air flowing across the bowl vents and venturis. But your setup sounds fine. Got me stumped.


At steady TPS 1900ish RPM 90ish MAP 60 MPH no AE or PE and WB AFR swings about 13.9 to 14.9ish? Never steady?

I havn't looked at his log yet, but I don't think it is that uncommon for the AFR to swing that much, especially at open throttle with very little vacuum. Obviously CL will move like that, but I think even my Camaro would do that in OL. Like you said sampling whatever mixture is going by at the time and averaging them.

I am just dumbfounded by the high map and no acceleration. I mean even in my truck, with a bone stock 120K '90 5.7 and a 9' plow on the front, my 60mph cuise is only 25%TPS, 45-50Kpa. I would think he should have as much HP and torque as I've got, in a smaller, lighter truck.

[PJG1173]

your not the only one stumped. I know this thing wasn't ever a speed demon but I don't recall it struggling to do 60. Tonight I'm going to see if I can slow down the sampling rate of the WB and see what it does. I know in my VE table VE dosn't really climb until 2800 rpm. the high MAP readings also only happen when the TCC locks, so I might try moving the lockup point to like 75 or 80 MPH and see if that changes anything.

[EagleMark]

the high MAP readings also only happen when the TCC locks, so I might try moving the lockup point to like 75 or 80 MPH and see if that changes anything.D'oh! :homer: with that 2075 RPM stall tourque converter that would give you the few hundred RPM needed to get that cam in the power band! :thumbsup:

[PJG1173]

:homer::homer: I'm an idiot. I didn't calibrate my DRAC/VSSB for the new 36's I put on a few weeks ago. :mad1: with the flip of a couple dip switches at 60 MPH im at about 30% tps and 86 kpa vise 95~100. I figured going from 35 to 36 wouldn't be a big change but the rev's per mile were way different which threw the speedo off by a large margin the faster I went.

[EagleMark]

Wow? That's a good improvement! Wonder why we didn't catch that in the data log? Still think you'd do better without TCC lockup as well till say 70 MPH? Then you'd be in the RPM range of that cam!

[PJG1173]

there would be no way to see that in the datalog since it refects what the vss is telling it. I think I'm still going to bump lock up higher in 4th. I don't have 4th comming in until 50 so when i get lockup in 3rd at 45 it cruises nicely.

[EagleMark]

I'd definatly play with those settings. With that cam and stall tourque converter I'd think no lock up at all in third and only at 70 mph in OD would be good? Keep that motor up there in RPM range of cam to be responsive. Face it, it's not a MPG vehicle. TCC was for MPG. In your case use it as a fifth gear.

[gregs78cam]

30% sounds much more reasonable, with a V6 the 86Kpa also makes sense. Cool glad ya got it.