Help diagnosing car missing and sputtering!!

3.8L V-8 eater

Well-Known Member
Joined
Jul 22, 2006
Well this problem surfaced last summer and went away only showing up at the top of the track my last time out in the fall...Did a few upgrades putting on a front mount and installing a Bailey's extreme chip...

First time out this spring the sputtering and bucking /missing is back...Most times it only shows up as it ramps into boost other times under light throttle during regular driving conditions...Sometimes a check engine light sometimes not!! No mal codes

Here is a list of things Ive done thus far:
1. Tried a known good coil pack and module
2. known good ecm
3. Tried both my TT chip and Bailey's chip making sure translator settings were changed
4. Verified grounds behind the pass head, checked wires going to starter
5. Put on a known good ls1 maf
6. Put on a new TPS sensor
7. Checked all i.c. hoses, maf hoses, and vac hoses
8. Checked connections on the back of the alternator and traced hot wire all the way back to connections at the tank.
9. Unplugged cam sensor to drive it in batch fire went into boost gradually maybe 5 to 7 lbs and it back fired and loud pop out the exhaust and the car shut off...Plugged back in the cam sensor car started right back up...Is it normal to do this in batch fire?? Is batch fire only to limp a car home ??

Dying to get this car back to the track with the front mount and I ported the housing on the turbo to get the boost creep under control..Any help appreciated!!!
 
Mine did the same thing years ago.Called everyone I could with and got all the answers on the things you have already eliminated.Called Dynotech and he hit it right on the nose being the cam sensor.He explained it to be play in the cam sensor shaft,I replaced it after having the problem for about 6 months and the car ran better than it ever had.Hope this helps!!!1
 
I know this sounds stupid but try a set of fresh spark plugs. Mine was doing it under boost only and plugs fixed it.
 
Mine did the same thing years ago.Called everyone I could with and got all the answers on the things you have already eliminated.Called Dynotech and he hit it right on the nose being the cam sensor.He explained it to be play in the cam sensor shaft,I replaced it after having the problem for about 6 months and the car ran better than it ever had.Hope this helps!!!1
I was wondering about the cam sensor which is why I unplugged it to go into batch fire...I do have one to try so I'm going to start there..If no dice will onto the crank sensor...
 
UPDATE

Changed out both the cam sensor and crank sensor no change!! Whatever is going on is getting worse...When warm the car will hardly even run...I put it in gear and it just sputters then shuts off...
 
Verify correct fuel pressure and at WOT. I had a bad FP autometer gauge once. Check plugs and see if it's running rich/lean and check gap.. Should be tight .032.
 
Verify correct fuel pressure and at WOT. I had a bad FP autometer gauge once. Check plugs and see if it's running rich/lean and check gap.. Should be tight .032.
At this point there is no wot as it will barely run....Going to change out the fuel filter next although I highly doubt that to be the problem....I do have a spare fuel pressure guage I can put on and I may be able to go on a short test run if I can get it in before the car heats up to much....The problem is getting worse and that may make it easier to figure out...The plugs definetly have a tight gap may have to pull them out again and check to see what they look like...
 
Need to see what your fuel pressure is doing, if that's good check to make sure your tps is reading right. Had a car the tps would make a big jump and car wouldn't run right. Or tps sensor could be falling as the pedal is being pushed.
 
When the car is acting up, shut it off, unplug each injector and check its resistance. If the resistance gets too low, it will knock out a quad driver in the ECM, and raise all kinds of hell. If it's barely running, it's likely a problem with a major input. MAF would be the first one that comes to mind.
What's your wideband doing during the issues? Rich, Lean? What you're describing, sound like it's running out of fuel.
 
Thats what I wondering. It has pressure but does it have volume? you have a datalogger and scanmaster and a wideband. what are they showing. The answer can be right there. Like gunslinger asked is it rich ,lean. I know your upset just step back and look at you numbers on the scanmaster or datalogger files and post them.
 
First off I want to thank those of you who have had input to help with this issue!!

Update:
I have always had a different reading in fuel pressure between the gauge on the rail and my K.Bell hood mounted gauge...Because it was easier to look at the rail gauge when setting pressure that's what I always went off of for the last 5 years...I have a spare k.b. gauge so decided to put it on...Noticed the pressure read itleast 5 lbs low just like the other one...This indicates that it is more likely the rail gauge is off so i set the pressure per the chip going off of the k.b. gauge...This meant I had to increase the pressure 5 to 6 lbs to get it at the 45lbs it needed to be...

After increasing the pressure I noticed it was blowing a some white smoke out of the exhaust...Took the car out for a drive and although it seemed a little sluggish and had a little more lag I was able to go heavy on the throttle without issue several times....Also seemed sluggish leaving a light but i know the chip was probably still making corrections and learning new values from the adjustment...Going to put in a fresh set of plugs tomorrow...I pulled a couple out after the test drive and they look like they were running lean....

Thing that gets me is why now with the issues when I have been going off that rail gauge for a long time??? Did have a TT chip in and it was having the same issues with it....Did it finally take a toll on the plugs???
 
Hey Tony, just wondering if you have a power logger? If not, you can use my stock ECM. I know its a long shot, but what the hell, im close. If it works, its yours.

Thanks Joe
 
I appreciate it Joe!! I did switch ECM's last weekend and th car still acted up!! Hoping new plugs with the adjustment of the fuel pressure does the trick...This last test drive was promising with no popping or sputtering....
 
3.8L V-8 eater said:
I appreciate it Joe!! I did switch ECM's last weekend and th car still acted up!! Hoping new plugs with the adjustment of the fuel pressure does the trick...This last test drive was promising with no popping or sputtering....

Mine as well do a whole tune up

Thanks Joe
 
First off I want to thank those of you who have had input to help with this issue!!

Update:
I have always had a different reading in fuel pressure between the gauge on the rail and my K.Bell hood mounted gauge...Because it was easier to look at the rail gauge when setting pressure that's what I always went off of for the last 5 years...I have a spare k.b. gauge so decided to put it on...Noticed the pressure read itleast 5 lbs low just like the other one...This indicates that it is more likely the rail gauge is off so i set the pressure per the chip going off of the k.b. gauge...This meant I had to increase the pressure 5 to 6 lbs to get it at the 45lbs it needed to be...

After increasing the pressure I noticed it was blowing a some white smoke out of the exhaust...Took the car out for a drive and although it seemed a little sluggish and had a little more lag I was able to go heavy on the throttle without issue several times....Also seemed sluggish leaving a light but i know the chip was probably still making corrections and learning new values from the adjustment...Going to put in a fresh set of plugs tomorrow...I pulled a couple out after the test drive and they look like they were running lean....

Thing that gets me is why now with the issues when I have been going off that rail gauge for a long time??? Did have a TT chip in and it was having the same issues with it....Did it finally take a toll on the plugs???

Well it appears the problem still exists :confused:.....I put a fresh set of plugs in it gapped at .028 and also changed the fuel filter....Today the car drove nice under normal throttle and hesitated a little under boost at about half throttle...The list of things I have checked or replaced is getting exstensive.....If this was weak springs or a broken spring It would not come and go or get really bad just at times correct???
 
My educated guess is that it's most likely a ground problem. Is your coil pack bracket powdercoated or painted?
Try running a new ground wire from your coil pack bracket to the fire wall and make sure you clean both ends. It's cheap and worth a try?
It could also be the coil pack? Do you have a coil pack checker or a spare coil pack to try?
Just a couple of thoughts? Good luck!
 
If you have a power logger ,scanmaster and a wideband. what are they doing ? Don't keep going wot if its lean you will hurt something.J&E pistons will melt trust me. Performance will not change intermittently with broken valve springs. When they are broke it will run like crap all the time.weak springs can cause problems but not the problems your having Did you check volume of fuel? It sounds like its running out of fuel. Is the wideband pegged lean when wot? scanmaster showing lean? Data logger info.Im not trying to be an ass but do you know how to read the datalogger and the scanmaster? there is a wealth of info right in front of you.If your lean you will see it on all three. I don't see any info about what fuel pump your using and don't say its stock.Do you have a hotwire kit? You are moving a good amount of air. I would have a double pumper with your mods just to be safe. I would limit on driving it or at least getting into any serious boost until you get it figured out. Start posting scanmaster info and datalogger files because if you need help reading them there is plenty of people on here that had the same problem your having and can probably help you figure this out just by looking at the info you post. Throwing parts at it might fix it but you can go broke in the process. Again not trying to be a jerk just trying to help. Like stated above check ground. run a jumper cable from battery negative to engine and run one from the body to engine and drive it like that
 
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