92 RS Camaro

Ok! Here goes. I have had my car for about a year and have only had minor problems since I bought. Now, please understand that I am not a certified mech but have worked on alot of cars and studied carbed and fuel injected cars alot. I have also done alot of research on this site to see if that would help. So far no luch.

Anyways, I have a 92 rs camaro with a 350 motor with a slight build (so I am told). THe problem is that when starting the car until you drive it to temp, it will surge idle or "fuel dump". After driving for a while (not shutting car off) it will run fine, idle fine with minor surges here and there. If you shut the car off you have to go through the hassle of the surge again. Now, only thing I really know about the car is this.... It has a 79 350 block (verified by numbers), 96 cast iron vortec heads (verified by numbers), and tbi intake (guessing from truck since the cars didnt come with that).

I have had the ECM replaced, TPS, EGR, and PROM. Still no fix to the problem. Anyone got any ideas as to what would cause the so called "fuel dump"? Also my gas goes out fast when this happens as I have to stand on the throttle to keep it running at first. I would like to fix this first, before I go out and buy a motor and still have the same problem. I am thinking fuel pump, but could be wrong. No codes are showing in car and SES light only comes on breifly and goes off just as fast. I was thinking swap to carb, but afraid still might have problem. Any suggestions????????

IROCmenace

iTrader: (1)

Is teh Prom a custom burned one? With that setup a stock chip would't work.

RFmaster

92 RS
The best way to troubleshoot this type of problem is to get yourself ALDL cable (do a search here or Google ~ $30 to 80 depending on a source) a laptop running WinALDL or TunerPRO (both are free) and perform an extensive data log from a cold start and until engine is fully warmed up and a short drive ~ about 20 minutes should do. Before you do that please post your ECM service number and broadcast code of your EPROM.

Otherwise there will a lot of guessing as too what is really causing your surging idle. In case that you have a custom burned EPROM will have a take a close look at it, but at this stage let take a look at what your ECM sees and how it reacts.


//RF

92 RS Camaro

Not sure if the PROM is a custom one or not. THe guy I bought the car from stated it was a stage two chip. I am planning to have the motor rebuilt here soon. If I do, should I have the guy write down all the stats on what he does to it and have a chip made for the car?

As for the ECM, the mech called the chevy dealership and got the computer that was to be in the car. Apparently the one in there was for a V-6 and locked in limp home mode. The other ECM I had was from a 350 TBI Roadmaster. I heard these we interchangable with my car, but the mech couldn't get the ECM to do anything except flash the SES light quickly.

RFmaster- Where do I find the broadcast code for the EPROM and service number for the ECM. I have an idea as to where the service number is but I just want to make sure I am giving the correct information.

RFmaster

'92
Looks like you have mail order chip in your original ECM (Stage II is not something GM would put in) Take a look on the ECM cover - next to ECM service number there should a broadcast code (BCC). If it is re-manufactured - refer to re-builders catalog.
1) Broadcast code is a four letter sequence which identifies EPROM configuration. It appears that GM assigned BCC identification sequentially, in some what chronological order. IIRC original ECM for '92 should have been 1228746 and there are numerous BCC depending on emission calibrations. Buick Roadmaster used LO5 engine, but it was equipped with 16136965 ECM. The ECMs are similar, but there are several differences ( I have cross ref info somewhere)

//RF

92 RS Camaro

RF,

After getting a chance to finally get in and look at my ECM and EPROM, here is what I have found. The ECM is remanufactured. From wheere is unknown. This is what the label shows:

number- 7-8746
DC code 0208MT

inside by the chip is this- 07874600080310023 REMFG

No broadcast code on ECM.

Looking at the chip, it is from TBI Chips, so I dont know what was put in there. but here is what is written on the chip.

TBI Chips
HOT
Copcar

Now I have come to realize that I also have an exhaust leak on the drivers side due to a bolt being out. Also the ECM for the Roadmaster that I have is a Remfg also. It also has no BCC on it. SO how do I go about finding what the BCC is? Also, I just got my laptop back up, damn hard drives!, and will be ording an ALDL cable after the 15thso I cna start to do datalogs. I really and looking into doing a rebuild of the complete motor. DO you have any suggestions with the setup that I have that will still allow me good horsepower without sacrificng way too much fuel? I really do appreciate everyones help!!

92 RS Camaro

To my surprise!!!! I urge anyone who have a mismatch motor like mine to pay close attention to this!!! I bought my camaro from a "mechanic". He told me he built the motor and tranny that was in the car. I spent this weekend doing minor tune ups after the car died on me in the middle of a drive thru and didnt want to restart (eventually it did with a lot of persuasion). Anyways, I went and bought plugs and an open element air filter to compensate the motor since the idle was wrong, very rough and would shut off constantly. After putting in 3 days of work to get the plugs in behind the headers, I fired up the car. To my surprise!!!- the car had the wrong plugs. The so called "mechanic" put plugs in from a 79 model motor instead of the vortec plugs that are required by GM. Now, I still have a small idle problem, but no where near where it was before. Now it only fluxuates between 800 and 1000 RPMs. If anyone seems to have a similar problem with their motor, here is what all I did.......


-Change plugs to AC Delco Platinum
-Adjust timing with new plugs
-Removed factory air filter system
-direct plug EGR valve to vaccum line from carb to bypass the electronic module
-removed A.I.R. system as it was never hooked up on my car

Hope this will help someone else out.