ok here is my problem. when i come to a stop or some times when i am changing gears my engine dies. it has been doing this for some time now and i am getting really tired of it. i have checked and double check every thing from tps readings to fuel pressure readings and they all have been within specs. any help would be nice.

 

Sounds like a vacuum leak. Double check you're vacuum lines (the Brake vacuum line in particular). Get you're hands on a gauge if you don't already have one, their pretty cheap.

 

I agree with checking for vacuum leaks. Is this on your 305 or on a 350? If it is on anything bigger than stock you could have more than mechanical problems. What injectors are you running. Do you have a 350 knock sensor? What kind of chip work have you done?

 

I think you might have a pickup coil/distributor shaft problem. Try disconnecting the timing lead for setting base timing and see if the problem goes away. If so I suspect the magnets on the distributor shaft are weak, this is a very common thing I see on tbi trucks. You should be able to buy that shaft from the dealer.

 

Also check the IAC, and make sure that the tip is clean, and that the location where it bolts into the TB is also clean. It's also a good idea to clean the full IAC passages.

 

Yes it is on my 350 Ok I don't have any vacum leaks, that was the first thing that i checked. I have a guage on it it seems to have plenty of vacum. I have 350 injectors, I havn't done any chip changes yet(don't have the equipment to do it) I iac is clean. I used to work at a parts store and looked at new knock sensors because when i changed motors we couldn't get the old one out so i had to by a new one. I also put about 1200 miles on the motor with out the knock sensor and never had a problem. That was about a year ago. This started about 2 months ago. The timeing is where it is suppost to be and was set the way it is suppost to be. So the only thing left to check is the distributor then? Would it just be easier to buy a new one then to replace the parts in it?

 

You cannot buy a new distributor from GM anymore for that and all the reman ones I have seen lately are all junk. I would just replace the pickup coil and the shaft in the one you have.

 

thanks for the help everyone. i will see what i can do on replacing the parts in my distruber. hopfully it will take care of my problem. I was told a while ago that the pickup has to be set at a certin place on the shaft or something along those lines is this true or was i fed a load of bs

 

scubas_90rs … have you fixed your problem yet.

My 91 Trans Am just started doing the same thing. It starts fine but when I’m slowing down to stop, clutch in … the check engine light comes on and the rpm’s are at 0. First thing I did was put some gas treatment in to remove any water but that didn’t help. Today I noticed that as I’m driving at 50, if I take my foot of the gas most of the time it dies … let the clutch out and it’s fine so it seems the spark must be OK. I got home and checked for error codes and there were none. Fuel pressure was right on. It’s a TPI 305 w/5spd. I think I’ll take a look at the IAC next … any other suggestions.

 

Jcpstrat no i haven't go the problem fixed yet. i don't have the income to buy the parts i need. I don't know about the over 50 deal for one I don't ahve to drive over 35 and two I don't know where 50 is because my speedo hasn't worked seince i put in my tranny so I don't know. but i do know that is doesn't die when i let off for the 35mph mark. I was talking to a macanic yesterday and he told me that i might have more than just distubtor problems. He looked at the car and told me that with not have any of the smog and egr stuff hooked up that could be part of my problem. He also said with that stuff not hooked up it is making the computer have misred readings. I am about to jus take the intake dis, and carb off my 83 and put on this becasue it is really starting to **** me off.

 

scubas_90rs … yep … things can get frustrating. I plan to check the TPS sensor and if that’s not it pull the IAC motor and clean it. I tried to buy a IAC gasket today but was told at the local GM dealer I had to by the motor to get the gasket .. around $79 I think. Anyway I bought some gasket material to see if that will work. If I find anything on mine I’ll pass it on. Good luck and thanks for the come back.

 

yeah good luck to you too

 

Well last night I checked the TPS voltage at Idle and WOT (engine off) and voltages looked good so I took the IAC (motor or solenoid?) out and it had lots of crud on it. Very carefully disassembled it and cleaned it and then took my T/A for a ride around the neighborhood … everything was perfect … started, idled & drove like a charm. Then I took it out on the interstate and after I got up to speed I pushed the clutch in and took my foot of the gas and the rpm’s went straight to zero again … argh. On the way back it also quit at stops. Every time firing right back up like nothing was wrong. Got home and checked for error codes and zilch … nothing. This is really starting to tick me off.

 

don't you just love it when you think you have somthing fixed and then a hour later or somtimes less it starts doing the same thing. i don't know what else to tell you. the macanic that I talked to the other day told me to drive the car with out the iac plugged in i have tried it yet but i might try that some time when i ffeel like openingg my hood.

 

scubas_90rs … my engine dying problems look like there’re solved. I ended up doing two (2) additional things. I bought that IAC motor and first measured the resistances between the AB and CD terminals on both motors. The old one had higher readings so I thought … ah ha. I installed the new one, pulled the battery terminal to clear all the codes and then started it up and let it Idle to normal temps. Then I took it for another ride and it actually was worse than before and it seemed like I could almost see my gas gauge going down … probably my imagination but when I looked at the driveway where I had it idling there were two (2) very black spots from the exhaust. The Check Engine light also came on so I checked the codes and got a 13, Open Oxygen Sensor Circuit. Some research said one of the things the Oxygen sensor does is to tell the IAC what position to go to in order to keep the car from stalling when the throttle changes abruptly. With about 8 hrs of patiently soaking the sensor with Kroil Oil and gently trying to get it to come out, it finally moved and I was able to replace it. Again I pulled battery cable to reset codes and let it Idle up to temp. Took it for a ride and it seems perfect, much smoother at constant low speeds too. Now when I’m at Interstate speeds and push the clutch in and take my foot off the gas it comes down to Idle much slower than before. Maybe the IAC and Oxygen sensor have been marginal for awhile or maybe I didn’t need to change the IAC but other than some time and frustration it wasn’t too bad $$ wise. Good luck with yours.

 

i don't think that my problem is in my o2 sensor. but then again who knows. with every thing that is going on right now i very well could be and just not seting off a code. that would be my luck. F**king car. It is going to be parked this winter so i won't have to screw with it till spring. and then it might still sit for a while untill i get tried of driving my 83 z28 that is going to be a little bit different.

 

Scuba,

I am trying to solve the very same problem you and JC have described. Mine started when I bumped up the fuel pressure since I was running lean at WOT. I've been tuning the motor all along and its running ok at cruise. BUT, when I come to a stop, it will sometime just flat dies like somebody turned the lights out. Sometimes it will go into a seesaw fit before it dies. If I turn into the driveway and try to "freewheel" the car into the garage, it will stumble and die. Since I have a Xfire, decided to replaced one IAC when the motor didn't want to run at all. That helped a lot so now its driveable. But when the motor starts to warm up, it'll get rough at idle and sometimes feels as if someone else is running the accelerator. I swapped O2 sensors about a 1k miles ago. Checked for vacuum leaks but the scantool says I am pulling 45kPa at idle. I'll keep you posted.

 

Good luck Dominic ... any codes? Mine's still doing fine now.

 

JC,

No codes which is part of why its maddening. The condition doesn't last long enough to throw a code. I keep reading the excellent information that's provided on this forum (one of the best on the Net IMHO) and recently came across a post regarding "viscous oscillation". Its a condition caused by having too great a disparity in adjacent VE table cells. One other area I have focused on is the TPS% for Idle setting. I was able to report on TPS% by modifying the ALDL stream (Thanks JPrevost) and found that my TPS% at idle was 2% while the ECM was expecting to see 1.17% before recognizing idle conditions. That seemed to help. I modified the bin last night to smooth out the VE table and take some of the step out of the adjacent cells and also modified the SA table to +- timing on the "in-between" cells. If the weather cooperates, I'll take it out tonight and see what happens.

 

Sorry it took so long to reply to you Dominic Sorresso i have been busy with other things. I have just said screw it and i am going to park the car here soon because I have a feeling that snow is going to be blowing in the near future. I think what i am going to do is just pull my Tbi and put a carb on it. With all the problems that i have in the wireing that i have fixed i am just going to get ride of the tbi. I am a lot better at finding problems that system the with all the electronics that are on the car. that and I am going to have a lot of time to mod the car while it is parked. But thanks for the info on what else to look into.