Engine Cuts out and stumbles under boost...HELP PLEASE! `

[Nero328]

Ok, I apologize for the long post in advance however I have been searching and reading on the forum for the last three days and have gone as far as I can without someone giving me a new idea to look at. I just had Nick Micale and his engine builder build me a new 4.1 stroker and he wanted the car in order to tune the motor so I sent it to him. He also installed a DW fuel pump and billet sending unit. After he put the motor back in he went out and did a few test runs and was able to build the boost all the way to 17 PSI before calling it done since it is a new motor. Eric also burned a new chip for me that is good for 30 PSI and 114 octane fuel...that is what is in the car now. When Nick did his test runs everything was running perfectly and it was ready for me to pick up. The car sat in a trailer for a few days until I arrived to pick it up. Nick had to install a battery during his tests because my old one went bad so when I arrived I installed a new Red Top Optima battery which is reading 14 volts. I went out for a test drive and as soon as the car starts to build boost the engine cuts out and stumbles. Nick and I (along with one of his buddies Dennis) began to eliminate potential culprits one by one and I still haven't figured it out...it is still doing the same thing. Here is what we have done so far. Keep in mind that after we tried these things I went back to the original item after it was confirmed that it was not the culprit. It should also be notes that I am currently running Sunoco SR 118 fuel which is a leaded fuel however the O2 sensor is new and it is giving good solid readings.

1) Double Checked all ground cables including the negative terminal on the battery (all were good)

2) Replaced the ECM with a known good ECM

3) Replaced the Coil Pack with a known good one

4) Changed the chip to a known good chip

5) Replaced the Crank sensor with a known good sensor

6) Checked all plugs and plug wires making sure they were all good and all in the right place

7) Replaced the MAF with a stock unit

8) After that was not the problem I put my LS1 MAF back on and confirmed my translator settings which are
1) ON
2) ON
3) ON
4) OFF
Dial settings are all at 0

9) Checked PowerLogger file, all numbers are within acceptable ranges including BLM, O2, Fuel Pressure (Verified with in car AutoMeter gauge which is 43 PSI with the hose off and it is rising with boost), EGT, TPS rises smoothly and maxes out at 4.14 which is slightly low however most likely not the issue,

10) Checked all IC hose connections and they are tight with no leaks or problems

11) No knock is seen on the PowerLogger file or on the Caspers knock sensor in the car.

One more thing to mention, if I roll into the throttle rather than stabbing at it the engine will build boost a little longer and just surges a few times before stalling completely and having to be restarted. I am not sure if that is something worth noting or just an anomaly but this whole thing has been frustrating. I dont believe this is anything Nick did wrong at all, in fact quite the contrary, I believe Nick went above and beyond to try and help me solve this problem. At this point we have gone through all of the normal things you would check on these beasts...someone smarter than me will hopefully be able to help me get my baby back on the road. Any help is greatly appreciated and I thank you in advance!!

 

[bpman1234]

Did not read the long post but while the engine is running shake the ecm wire by the battery. Maybe its on its last string of wire.just a shot.

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[achalmersman]

You tried all those parts but not a known good ign module?

What plugs? Are they resistor core?

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[Boxcars]

Maybe you're losing your 12V power supply -- shorting somewhere as the engine torques and when you let off, it regains power, maybe in the vicinity of the fusible links connected to the starter?

 

[achalmersman]

Can you post PL file that shows the symptom?

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[Nero328]

You tried all those parts but not a known good ign module?

What plugs? Are they resistor core?

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

Good idea, I double checked that after you mentioned it but unfortunately that wasn't it

 

[achalmersman]

Which one? So you mean you are using resistor core plugs right? Have you tried a known good ignition module?

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[Nero328]

You tried all those parts but not a known good ign module?

What plugs? Are they resistor core?

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

yes, I failed to mention that we tried a new ignition module along with the coil pack...I know the post was long but I was trying to give all of the information I could so I didn't wast anyone's time.

 

[achalmersman]

yes, I failed to mention that we tried a new ignition module along with the coil pack...I know the post was long but I was trying to give all of the information I could so I didn't wast anyone's time.

Gotcha. Can you post a log for people to look at?

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[Nero328]

Good idea, I double checked that after you mentioned it but unfortunately that wasn't it

sorry, I double checked the power wire to the ECM, that wasn't it. I nkow the plugs are NGK but I didnt pay attention to which one. Also, yes I failed to mention that we tried a known good ignition module when we did the coil pack...both at the same time.

 

[Nero328]

I will have to get the log from Dennis, I forgot to ask him to email it to me last night. It is very strange because everything looks perfect on the log. I will see if I can get Dennis to send it to me tonight.

 

[Nero328]

As soon as the car begins to build boost it falls down as if you just took your foot off of the accelerator. It spits and sputters and pops until I do let off of the accelerator and then it starts running perfectly again, if I roll into the throttle it will run just fine until the boost builds again past 5 PSI and then the process starts all over again.

 

[achalmersman]

Just looked at your signature and it shows you having GN1 heads. I bet you have non-resistor core plugs / racing plugs. If you are not 100% positive they are resistor core plugs start there.

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[Nero328]

Just looked at your signature and it shows you having GN1 heads. I bet you have non-resistor core plugs / racing plugs. If you are not 100% positive they are resistor core plugs start there.

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

ok, I will check them in the morning but I know that these are the same plugs that were in it when Nick was out doing his test runs. It is certainly something I need to check and be positive about though. This is one of those extremely frustrating issues!

 

[achalmersman]

I would say its a safe bet you have copper core plugs in the car and not resistor core. Read this thread, where I finally found that solid core plugs were the cause of the problem, and 2 or 3 other people came to fix their cars as a result of this thread as well. The next to last post has the exact plug I will be running in my TA SE heads. And it took 3 weeks to get them.

http://turbobuick.com/index.php?threads/419814/

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[Nero328]

I would say its a safe bet you have copper core plugs in the car and not resistor core. Read this thread, where I finally found that solid core plugs were the cause of the problem, and 2 or 3 other people came to fix their cars as a result of this thread as well. The next to last post has the exact plug I will be running in my TA SE heads. And it took 3 weeks to get them.

http://turbobuick.com/index.php?threads/419814/

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

So the NGK BCR8ES plugs solved your problem? Since this is not a particularly easy plug to find I would assume that Nick most likely put a standard copper core plug in the car as well. I will order a set of these for sure however it is weird that it would run great during testing and then all of the sudden start having problems...I guess it could just be the plugs. What is the reason behind this plug being the solution VS a standard solid core plug? I am currently running very low boost just to break in the motor but I will be running ~30 PSI after break in.

 

[achalmersman]

Solid core plugs create a lot of RF interference and with the powerlogger installed the factory ECM is much more susceptible to that interference. In my case only under WOT conditions the ecm would reboot causing the condition you describe. I was running factory heads so different plug but it was solid core. Switching to resistor core fixed the issue. Resistor core is what our cars came with as do all modern cars. I call BS on the whole "racing" solid core plug thing anyway. I dont buy that changing nothing but the core from resistor to copper will gain any HP on a 6-700 hp engine. The potential headaches arent worth it for me. The reason that specific plug is hard to get us because of its specificity. Its 14mm, non-projected tip, resistor core.

I would still like to review your log during the issue

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[Nero328]

Solid core plugs create a lot of RF interference and with the powerlogger installed the factory ECM is much more susceptible to that interference. In my case only under WOT conditions the ecm would reboot causing the condition you describe. I was running factory heads so different plug but it was solid core. Switching to resistor core fixed the issue. Resistor core is what our cars came with as do all modern cars. I call BS on the whole "racing" solid core plug thing anyway. I don't buy that changing nothing but the core from resistor to copper will gain any HP on a 6-700 hp engine. The potential headaches arent worth it for me. The reason that specific plug is hard to get us because of its specificity. Its 14mm, non-projected tip, resistor core.

I would still like to review your log during the issue

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

Yes, I will definitely post the log as soon as I get it and if he doesn't send it then I will go out and record a new log tomorrow and post it. I am not convinced yet that the plugs will solve the problem however I did order a set from the link you provided (Ninja) I sure hope that fixes the issue though. While typing this I remember that I also swapped the ECM out with one that did not have a PowerLogger installed and it didn't get rid of my problem so I am not holding out much hope for this one but I will try anything at this point! I appreciate your time and effort, I will post a log as soon as I can.

 

[dynoman]

I had this exact same problem . I switched to non-resistor core plugs and had this problem immediately , switched back problem went away .

 

[Chuck Leeper]

http://www.ebay.com/itm/10-PCS-NGK-...ash=item1c5034a4d4:g:j9wAAOSwPhdVEklb&vxp=mtr

Looks like the guy I get my plugs from, has them. And, at a good price.
Just got a spare set for the LS project. Took 4 days.