Time for a tune?
07-05-2013, 08:14 AM
#1
Time for a tune? Car is a 93 Z. Stock engine, pacesetter LT's, flow master single exit cat back, FLT lvl 4 with a 3600 stall. Deleted the air pump and egr. Car has a stumble that drops about 500 rpm at random times under part throttle. I've put on a delteq system, new plugs, new opti, new delco o2's, and brand new tr55 plugs. Car runs just fine when its cold, but develops this stumble in closed loop. Idle also surges from 500-1000 rpm. There is no check engine light, and no stored codes. I'm going to check the Injector resistance on Saturday. Car has never quit running, just more of an annoyance to me. Anyone have any ideas where else to go with it?
07-07-2013, 06:44 AM
#5
So I'm gonna update this. So far I've put new o2's, iat, map, opti, plugs, and a fuel filter. When I pulled the plugs they looked great, maybe a bit lean. Car has full exhaust and an ls1 lid setup on it. Is it possible that I've just gotten enough air going in and out that its time to add more fuel since its that much more efficient?? I checked for vacuum leaks and didn't find any, all the injectors ohm out ok. I'm seriously beginning to think I just need a tune to go with the new trans/3600 converter and intake/exhaust setup.
What else could make the car think its running rich when its not??? Especially with clean plugs?
What else could make the car think its running rich when its not??? Especially with clean plugs?
07-07-2013, 08:45 AM
#6
A high stall will often cause some idle confusion for the pcm since it places less load on the engine in gear at idle than the stock converter did. This will also show up as some surging while coasting.
At this point though IMO you have a "which came first the chicken or the egg" a car needs to be in good running order to get a tune dialed in, but at the same time you already did so many mods you likely affected how the car ran. So you have to hope there is nothing mechanical going on at this point when he starts to tune.
Far as the Delteq, don't expect that to be really anything other than another problem for you, at best it was always the least functional "opti delete" setups and in reality they started failing and the owner of the company was unfortunately ill so he never came up with a permanent solution.
At this point though IMO you have a "which came first the chicken or the egg" a car needs to be in good running order to get a tune dialed in, but at the same time you already did so many mods you likely affected how the car ran. So you have to hope there is nothing mechanical going on at this point when he starts to tune.
Far as the Delteq, don't expect that to be really anything other than another problem for you, at best it was always the least functional "opti delete" setups and in reality they started failing and the owner of the company was unfortunately ill so he never came up with a permanent solution.
07-07-2013, 09:14 AM
#7
The real problem as far as I can tell is a lean miss/stumble while in lower (2500-3000) rpm and idle. It started with a crazy miss, which is where the delteq came in. New wire routing and an msd box for spray in the future. That killed the opti (which was original and needed to be replaced anyway after opening it up). Now I've been chasing this stumble which has gotten worse since the trans and converter went in. Most likely because as you said the load in the engine is different. Add to that the full exhaust and better flowing intake, and I can only assume I've hit the point where the ECM thinks there's something going on. At WOT the car runs fine, once again assuming, because the factory WOT tables are rich to begin with.
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07-08-2013, 07:36 AM
#9
Butch I'm down! I sent an email to Ion yesterday so we'll see what happens. I'm gonna try and run the bracket class out at Byron the 14th. It'll be a bit different as its on the pro tree. Oh well. With all luck I should be able to walk away with some money, as long as the car doesn't go too fast. LMK when you're going out to GLD again and I'll do my best to get there.