Hey just wondering if anyone else has experianced this?? I have got everything in tune pretty good just making some slight tweaks now. But every now and then after the engine sits for a couple of hours and cools down, I will fire it up and it will idle fine, slightly high do to coolant temp, Then when I go to put it in gear it will drowned it's self for a half a second or so. It will only seem to do this when it is not completely cold and not hot. But when the engine has been run for a while and it cools down enough to not read on the tempurature gauge. Could it be a leaking injector pod or something to do with my programming?? Im using an Airgap manifold and the ecm is a 7747 running a $42. Engine has a slight cam and other mods. Its just weird how it only does it at a certain temp!! Please any suggestions??

 

Its certainly a possibility, especially with an airgap. It could also be a lean issue. If the airflow drops and the MAP rises suddenly, then you can run into a situation where the fuel settles out onto the manifold walls due to the rise in the MAP and poor air velocity and leaves the engine too lean, which will cause the idle to drop like a rock and the engine to want to stall. This is especially a problem in the winter. Mine does it once or twice in the first few minutes of operation in sub freezing temps. If its a lean issue, it could just be the nature of the beast with an unheated manifold. How does it act? Does the idle drop off and stutter for a bit, and then recover? Does blipping the gas help? Does it pop at all?

 

It is definatley a rich condition. NO popping, it will stuble and you can see the fuel come out the tail pipe. Tapping the gas will help a little but only because it seems to clear out a little when the throttle open's. I think that it could have to do with my coolant temp/ae settings. Not sure though. Thanks for the reply and I may just have to live with it I guess.

 

You can actually see/smell raw fuel out the exhaust?

If thats the case, then there is definatly an issue that should be resolved (no good for the motor). It would also likely stick out at you as well. Whats your AE temp correction look like? Is the VE real high at low RPMs/high MAP? Can you datalog your injector pulsewidth?

 

My Ve table is real good at that rpm and pretty much all rpm actually. I have it within +- 3 in the hole table. As for my Aevscoolant it is set a little higher than stock by about one full point from 15% up about 45%degrees that is. Maybe i should lower that back down to normal?? I can only see the black smoke as a put it into gear. But it is only there at a certain tempurature. I just havent figured out what temp that is yet. Not cold and not warm/hot. Im thinking around 30to40 dregrees. Thanks again Demented.

 

Sorry forgot to mention im using tunerpro as my editor and datalogging with winaldl. So at this point i dont know how to datalog my pulsewidth.

 

Hey Dimented I just went and looked at my Ve table like you said and Maybe your right about low rpm high map. My 400 rpm 70to100 map is in the 29 to 37 range and 800rpm 70to100 map is 40to50. Main Ve table that is. Maybe I should try reducing those area's a little?? I didnt think that area affected much but now that you mention it. I would think that when I go from a 950rpm in park to 650rpm in drive that the map would go up quickly and then settle down at idle causing a rich condition. Im I right to assume this?? Thanks again.

 

Too high of a VE can cause the engine to go too rich as it crosses into those areas. The VE sounds reasonable, but who knows. It could also be an excess of MAP AE. I dont remember the specifics of whats in the 7747s, but the MAP AE is usually engaged whenever the MAP rises. If theres too much, itll cause a rich condition. It could also be something entirely unrelated. Datalogging the pulsewidth, CTS, and MAP during an event will help shed some light on whether its a problem with the VE, AE, or something else entirely.

 

Thanks for all the help Dimented!!! I will look into those and see what happens.

 

You might look at IAC AE. If you have gone to bigger injectors or raised the FP too much, you could be getting too much fuel on the IAC jump from park to drive when mixed in with the MAP AE. I know I have had this happen to me, especially when going to different heads than stock. HTH

 

I dont seem to have that option in my $42 xdf. I am running more fuel pressure though and have tuned for it. It only seems to do it until the o2 lights of. After that it seems to be fine.

 

Ooooh! $42. My bad. For some reason I thought we were talking about a later a TBI PCM. The $42 mask does not have this feature. Nevermind.

 

I just got a new GTA and am having a similar problem. Raw fuel is coming out the exhaust pipe. It runs very poorly until it reaches a certain temp and then instantly starts running better (but still rich). The interesting thing is that I just had new exhaust put on. It didn't do this with the old exhaust. However, the old exhaust had a "modified" cat. Completely gutted. The new exhaust has a functional cat. The engine is heavily modified and has a large cam 230/234 and 528/539 w/ 10 lsa. I'm assuming the problem is in the tuning, but I don't know where to look. I just ordered my burner and am new to chip burning. I know I'm not going to get the perfect chip right off the bat, but I would like to at least get it to idle and be safe (my bumper caught on fire from the fuel!). Anyway, does this sound like a chip problem, and if so, where do I begin?

 

Hey I would just like to clarify that there was not raw fuel coming out the tailpipe but just black smoke I.E Very rich. First of you must have had some sort of chip burned or changed in order to run that cam??? Or are you MAF style ecm?? Do you know what ecm you are running?? I would check you o2 sensor to make sure that it is working, maybe it was damaged or unhooked during the exhaust install?? If All of your sensor are working you may have a bad injector or something else. If you are getting that kind of raw fuel out the exhaust something is definatley wrong!!!! Im sure that you will be able to make it run much better with some tuning and chip burning, but do you know the current state of tune in the ecm. Stock or otherwise?? Was the cam installed prior to you buying it?? If so I would say that you have some work to do. Many others Im sure will chime in and help out. Good luck and I wouldnt drive it to much like that. Fire hazard and that kind of fuel will be real hard on the engine. Change your oil lots. Hope this helps a little??

 

It sounds like the O2 is still working from the fact that it instantly runs better once warm. Sounds like the ECM is pulling as much fuel as it can. I wouldnt drive teh car much like that. Itll wipe out the rings in no time. What size injectors are you using? Is this speed density, or MAF? Have you made changes to the chip yet?

 

Actually, the $42 mask has IAC AE, location $293. When ever the IAC is opening the ECM will add a little extra fuel. As Hauln' posted with greater injector flow this value can be reduced. However, a BBC TBI unit has a larger IAC pintle opening. So if using one it doesn't need to be reduced as much.

Back to the original posters issue. Since you claim it only happens at this one particular engine temperature after startup, reduce the after-start (choke) enrichment at that temperature ($427). Can also speed up the decay of after-start enrichment at that temperature ($438).

Now, if this doesn't do the trick, or if it causes other issues, return the values back to what they were.

Then, reduce the MAP AE or total AE at that engine temperature ($306, $40C). Without being able to get a real datalog, it is difficult to know which is causing the problem unless tried.

RBob.

 

Sorry about that. Since this is a different problem I start a new thread so as not to divert discussion here.

 

Definition file updated. I figured it was somewhere in the cal but I overlooked it (twice) in the ARJU hack. Thanks for pointing it out.