Working on a 2000 C5 Automatic. Just installed a new Iron Block 408, DTE Stg. 5 rear-end, Rossler racing 4L65E and the RaceTronix Fuel pump with the plug-n-play wire harness and 42 ld. Injectors. And to top it all off a nice custom NX direct port pilled for a 500 shot with a progressive and a stand alone fuel system.
My problem is after installing everything; I cranked the car up to running temp. It ran nice. After that I killed it and let it sit overnight to cool. I retorqued the heads, and then took it for a ride. It was nice, but after 4 or 5 miles I started to notice a miss. I went home to check everything out. Now the car stalls after 20 sec. of idling, or if you try to put it into gear it stall, like you turn the key off....Any ideas???

 

Anyone?????

 

Thanks... Sorry for posting here. My problem just sems like a high tech problem..

 

Can you be more specific with the symptoms? Any new noises, like ticking, vacuum hissing... etc? Are the ground straps/connections all good?

Check all the standard stuff. Air (unmetered, vacuum leaks), Fuel (Injectors working, fuel pressure), Spark (plugs, wires, coils). Also the tuning for the engine. Is it throwing any codes?

A/F, is it running rich or lean?

 

The car sounds great. It idles like a beast. But after about 20 seconds or so it stalls. Or as soon as you shift it into gear (It is an automatic.) it stalls. I did get to drive the car for about 5 miles once everything was installed. It seemed to run great until we noticed a little miss. We had the wrong plugs in. So, we changed them and installed the proper plugs and then it's been hell ever since. Maybe all a coinsadence, but I'm lost. Moe the tuner is lost, and nobody seems to know.... After all this money, I'm pissed....

 

sounds like A converter/ throttle body / or tuning problem. Or all of the above.

If you've determined it's not a vacume leak, list what you have for the following above things. Who tuned the car?

 

Our H/C car can be tempermental sometimes while cold starting, and will do the exact same thing. It is a tuning issue IMHO (our issue), and just the nature of running the beast. Our car prefers to stall while going into reverse, or cold with any gear and the power steering pump working.

Are you letting the car warm in idle before putting it in gear?

Like DannoWS6 said I think it may just be a tuning issue, have you tried bumping up the idle rpm a little?

It may not be getting enough air at idle. Don't necessarily drill the TB plate, but is it a stock 78mm TB with a bumpstop mod for a little more air or a Fast/NW/PTM 90mm TB?

I see you have a built tranny, but what converter are you running? The stock converter likes things that idle around 700rpm, but you may need to verify the idle in gear with the tuning software to make sure the load from the verter is not stalling the engine. With your setup I would be running a 4000+ stall verter, but that is just me...

Also the 20 seconds stall, seems like an idle down issue, but I am just shooting in the dark here. I would ask your tuner to tweek the idle RPM and see what that does...

 

Thanks guys for all of your help.. The throttle body is stock, it was ported. The converter is a new Precision 3400. As for letting the car warm up, it stalls way before it can warm up. I'll have the idle double checked. But what gets me is, right after I installed the motor, tranny, converter and rear-end I started the car. It idled great all day long. I turned the car off and let it set over night, then re-torqued the heads the next morning. I started the car, and drove it for 5 miles. No problems at all. Then after realizing that the plugs were the wrong plugs, and after changing them, these problems started.... I'mmmmmmm sooooooo lostttttt!!!!!!!!!!!!

 

When they ported the TB did they epoxy the IAC hole? Iv'e seen it a bunch of times especially on H/C cars when the hole is covered too much. Just need to drill it out a little.

Maybe one of your wires is not corectly on, possibly arcing? Although is does sound more like a vaccume leak.

It is tough tuning the converter/cam to behave at idle especially if you got a tight lsa or low vacume. If you can get the car started, hold the idle w/ the gas and drive it around to establish it's not a plug or vacumme leak. If you can confirm the car drives fine, just won't idle. Then do an idle re-learn, and remember not to touch the gas when it's trying to find idle or you will kill the process. If the car won't catch idle after a while then it needs to be tuned again.

Check that TB though.

 

The IAC hole on the throttle body does not have epoxy on it. As for the car driving right. It drives BAD. Something big seems wrong. I just can't place my finger on it.

 

Recheck engine grounds. Oh does it have a known quantity of fuel in it ?? sounds like a fueling type of issue.

 

Check the fuel pressure. It is a pain but check to see if one of the plugs was damaged or cracked. Coil or engine harness malfunction, make sure they are all firing. Check plug wires with a mutlimeter for resistance. Recheck engine ground straps. Check the A/F ratio...

 

I just installed new wires, plugs, injectors. I know it's not the tune. The car ran great right after assembly. But when I changed the plugs the first time and pulled the intake to reroute the coolant line that runs under the intake, I put it back on, and that's when the issue started. So, I'm thinking the vaccum lines that run from the front pass. side of thee intake to each valve cover are some how backwards, or something. That's all I can come up with. I have it at a local shop and they are going to hook up a scanner to see what they can find.

 

If that's when your problem started you need to retrace every step. Check the obvious; make sure the plugs and plug wires are on snug, intake seated and torqued correctly, MAP sensor, small vacuum hose on intake installed, etc.

 

Does the car have any tune for the 408 and the injectors?

If not the car would have started with the old motors tune and fuel tables, then after a relearn period your fuel tables were reset and now the car runs like *** because of lack of tune.

 

I didn't know that could happen. I sent my PCM off to Moe Bailey, he gave me a base line tune to break the car in properly. I'll get touch with him, and check what he did...

 

I just got some info, me running opened headers may have toasted my O2's, and now my car would run like $h!t with bad O2's. I'm getting the exhaust done this Thursday. I'll get new O2's as well. But, does this sound right??

 

It can but you will throw a code if it's that bad, insufficient switching, heater circuit error, etc.


Are you sure you didn't damage the MAF taking it all apart and then back together? Try swapping the MAF, worth a shot.

 

I'll try that as well. You do mean the MAF and not the MAP right???

 

Yeah Mass Air Flow sensor. Try swapping with a buddies and see if that helps. If the wires are damaged that would cause problems.