What do I gap my plugs at?

[The_Ghost]

I'm finally going to replace my spark plugs. I've been told for a while that this is my cold driving issue I'm having. Of course the kick in the pants was almost getting killed pulling out into traffic one night after work with only letting it run for 30 seconds or so before I left!

So as some of you know, I have a tune....which one I don't know.... I get 21psi of boost, have a high flow cat and solo race exhaust. I'm going to use the factory AC Delco 41-108 plugs. The reason I'm asking is there seems to be a lot of opinions in earlier posts but nobody really nails it down. The guys over at hptuners say .028 - .030. I've heard .035 here and read anything from .017 - .044 on these forums. Bottom line....I need to know what will work best! Thanks for the help!

[GS Stage 1]

My Redline with GMPP tune likes .032 the best.

Some have ended up running a little tighter to avoid "spark blow out" with the higher boost of a tune. At my altitude (5000 ft above sea level), my car will pull upwards of 26 psi under full load in the summer: And I have not experienced any spark blow out issues. But every car is different. If you start having misfire issues in the summer at WOT, then try reducing the gap just a little before you go messing with anything else.

[KappaKadet]

Also went with 32 and the new Delcos came that way straight out of the box.

[GS Stage 1]

Ghost:

Be sure that you are not misinterpreting your cold engine-lack of boost issue. The ECM does not allow full boost to be commanded until the engine reaches at least 180-185 degrees operating temperature, as an engine protection protocol.

Typically "spark blow out" problems will tend to show up with peak boost at WOT and tend to be more problematic during hot summer days when the ECM has to command even more boost to offset the lower ambient air pressure.

[The_Ghost]

Originally Posted by GS Stage 1 Ghost: Be sure that you are not misinterpreting your cold engine-lack of boost issue. The ECM does not allow full boost to be commanded until the engine reaches at least 180-185 degrees operating temperature, as an engine protection protocol. Typically "spark blow out" problems will tend to show up with peak boost at WOT and tend to be more problematic during hot summer days when the ECM has to command even more boost to offset the lower ambient air pressure.

Thanks!!!! I asked that question when I first noticed it and everyone said that there was no protection built in to stop it from full boost. The issue I have is that if I try to pull out in traffic, my DIC says 21psi, but the car literally feels like someone threw an anchor out the window. You can hear all the boost coming out the exhaust, but the car absolutely dies and gets slower then if I didn't get into the boost when its cold. Thank you very much for the info!!!!

[GS Stage 1]

As you have described your symptoms in your most recent post: This does not correlate to what I have observed as the built in protection protocol during cold engine cycle.

As I have observed: During cold engine cycle protection (pre 180-185 operating temperature) the car will not pull boost above anywhere from 5-10 PSI. Otherwise the car will run normally. It is not sluggish or slow. It just will not pull max performance because the ECM is limiting peak boost command until operating temperature is above the 180-185 range.

The only other thing I can think of is if you are jumping in and taking off while the engine is dead cold: The ECM also runs a cold start CAT warm up cycle in the first 30 seconds to couple minutes. When you first start the car, and it is dead cold; the ECM will command a high idle and it also runs A/F pig rich. This programing is part of the emissions requirement to quickly heat up the CAT. If you tap the gas, the car will typically drop down to closer to normal idle, but it does still seem to be running on the rich side. If you were to start the car and immediately drive and demand throttle, the run rich status may cause the symptoms you are reporting. However, I have never observed such symptoms personally. I tend to always let the car drop down to normal idle before I take off.

The only other cause I can think of that could be the source, but not necessarily throwing a code or CEL yet: If the CAT is just beginning to fail and causing excessive back pressure, that could cause the symptoms as you have described them. The CAT could be just marginal, but after it warms up the restriction lessons and you have normal operating again.

[The_Ghost]

Interesting. Maybe it sticks in the CAT warm-up phase? I can hear all the boost coming out the exhaust. I do have a high flow CAT (I think). That's interesting. I bought the car 4000 miles ago and have had this issue since. After I get on it the first time...it's fine u. I usually let it run for 3-4 minutes before I leave. I live in Michigan....

[The_Ghost]

Changed the plugs....no difference, other then I have a surge at idle when its cold... I did find out that I no longer have a rev limiter.....and that the little engine survived its first dive past redline.... Not that I'm proud of the fact, but I got it past 7200 last night before I realized I was that high....and the scary thing was the car was still putting me back in my seat.... So, I guess I need to get a tuner kit from hp and "fix" some stuff. A buddy that is a seasoned tuner with turbo cars says it might be the knock retard until the engine hits a certain temp giving me the issue. I won't know till I get the tuner items......