As most of you guys know, I rebuilt the engine on my 84 (auto trans equipped) and have been getting everything dialed in with the car over the last couple days. Yesterday, I broke the cam in and set the timing. I then took the car for a short drive. after about two passes down my street I noticed that the engine would stall as I were coming to a stop. It ran and idled fine until I drove the car. Chek Engine ligh was on the moment I started the car and was on when I bought it. I replaced the fuel filter, air filter, plugs, ALL engine gaskets, and ensured everything was torqued to spec. I'm looking for suggestions as to why the engine would stall after being driven. do you guys think that the issue lies in the following:

-clogged IACV
-vacuum leak
-weak fuel pump or fuel pump feed hose located on the pickup assembly
-bad EGR valve

Just looking for hints or suggestions

 

Like AmericanVette was saying in the other thread, as the engine warms up there is less oxygen going to the cylinders at the same throttle positions, assuming the IACs are the same. My guess is that the IACs are not opening enough when the engine warms up. (I'm not sure what, if anything else, allows more air into the cylinders as temperature rises.) I definitely believe it is a "too much gas, not enough air" problem. It could be the different cam, possibly higher fuel pressure, ECM issue.

 

Check fuel pressure first. Not an easy thing to do on a crossfire.

Run a fuel pressure gauge hose between the TBI's and tape it to the windshield. In fact, take your crossover tube and a 0-15 psi gauge to a hose and tubing shop and have them fab in a fitting on both to test fuel pressure on the crossover tube. This way you can check fuel pressure EASILY on your crossfire whenever you want....and you can watch in while you're driving the car for diagnostic purposes. This is the FIRST mod anyone should make to a crossfire....

Here's my old setup...

 

-Does the car/motor run well at a cruising speed? Say above 30mph?

-What is your idle speed when cold? In park? In drive?

-What is your idle speed when hot? In park? In drive?

-Have you pulled codes with this CEL? What are they?

From your posts in the other thread it appears the motor starts easily and idles fine cold. If it runs well at cruise speeds above 30mph, I would say you are very close to having everything sorted out.

Since your car is basically stock, with mild cam change and transmission/torque converter changes, I would start with the trouble codes. They are going to tell you why the ECM is not happy. Its a PITA, but I would try to clear those codes first. All of your listed possibilities are definitely viable culprits to your problem. The codes should tell you which path to pursue. Good luck, grasshopper. I and others will try to work this thru with you.

 

Take the dog's (Friz) suggestion first.

 

Another random thought that perhaps Frizlefrak can answer. On the L98, the throttle position sensor (TPS) has a very specific voltage that it needs to set at. Is there a such a requirement on the crossfire?

On the tuned port motors a miss-adjusted TPS causes all sorts of goofy problems.

 

Friz has been posting and making a lot of excellent points. I didn't have a lot of time befor eI went into work tonight, but i did bump the timing to 10 degrees. This helped matters. When I started the engine, it ran ok and I had to crack the throttle, as always, to get the thing to start. And then i held the throttle open a shade and then it idled ok. Cold idle was 900 rpm in neutral.

I then took the car for a drive down the road and it ran without hesitation and shifted fine. when I slowed down, the engine idled at fluctuating 400 and 500 rpm. Progress was made by bu,ping the timing. The engine no longer stalled. This however is just the first step in solving this idle mystery. I don't feel as though I should have to hold the throttle on cold start. If the car wre carbureted, I could see that i would need to do as such.

To sync the throttle bodies, it seems as though I wil need to locate a manometer. I also looked in the FSM and saw how to mechanically open the throttle bodies. This owuld no doubt help matters but I feel as though it would be merely masking my problem. I still feel as though its a vacuum issue having to do with the cam install. I'll fix it though. The engine sounds awesome to me

 

Yep, sure does. And it needs to be correct or the car will run goofy.