need assistance.....

[grease monkey girl]

ok, this is going to be a long post, so please bear with me.
For starers, I drive an 87 Iroc
A few weeks ago, I was driving on the freeway when I noticed that my rpm's were fluctating up slightly - this was not constant, but disconcerting nonetheless. I decided that it must be the spark plugs. I changed those - not the problem. The fluctuations became more frequent. I decided it was the fuel filter, so I changed that - not the problem. The fluctuations became more frequent, coinciding with a noticable "chug-ch-ch-chug" that is not necessarily a hesitation, because the rpm's fluctated up, not down. We decided to change the spark plug cables, and cap and rotor. On further examination, the ignition coil seemed to be sparking, so we decided to change that as well. All this being done, suddenly the "service engine light" comes on, the rpms drop way down, the car sputters and dies. Checking the codes, it gives us code 51 - ECM/PROM malfunction. On top of that, the new coil is sparking as well as the new spark plug cables. Now what I want to know is this - could there be another problem with the electrical system that would cause the codes to read 51 other than the ECM? My uncle could swear it is the EGR ( I think), but we can not locate that on the car. And if not, could a bad ECM have caused the spark plugs to short and start leaking, or did I buy defective wires? And how much does a standard ECM for an 5.7 engine run? I ended up under the hood of the car for well over 18 hours this weekend for what I thought would be a routine maintenance problem. I am sort of at my wit's end and don't want to have to take it to a mechanic. My uncle and I ran across this discussion forum and you guys (I'm using a generalization as I know there are a few ladies here as well) seen to be pretty knowledgable, so I am hoping for some assistance.

[Hypsi87]

Change the EPROM, sometimes moisture and whatnot can get to the E PROM and kill stuff, Also, Did your EPROM see any sunlight? If an eprom does not have the little sticker over the eye of the chip, sunlight will erase it. Well, it would take about 2 weeks of direct sunlight to completely erase a chip but partial exposure can damage some of the drivers on the chip. Also some of the injector drivers in the ECM could of been damaged as a result of moisture. I would change the ECM. Check for any pinhole leaks, and trace your wires going to your ECM and make sure that there is no chance for water to get to the ECM. I went through about five ECM's and it turned out that water was dripping down from my heater box (It had a bad seal.) and following my computer wires down to the ECM.

[grease monkey girl]

I don't think it is moisture, I looked up under the dash where it is located and it's dry with no visible water damage. The sticker is still over the chip area as well. My concern is also whether the eprom would cause my spark plugs and coil to blow.

[89IROC&RS]

well, another ignition component to look at is your ICM, its the small module in the distributor under the rotor, that the two plugs connect to on the back. mine just crapped out and caused the same problem you are having, with idle surge, low speed stalling, and misfiring, mine turns out to be an aftermarket peice of crap, but GM ones will fail too. however mine didnt set a code.

Im assuming your 87 is a TPI engine, if so, your EGR valve is being "hugged" by your intake. its in the center of your intake baseplate, in between the runners, and under the plenium. you have to remove the plenium to get it off. i also had this problem on the IROC, and turned out it was a leaking diaphram.

For the ECM failure, its not that big of a deal, i think you can find them on ebay for 50 bucks or so. and they are easy to swap out. so even if you buy it, and it dosnt fix it, you havent waisted aot of time, and you have a spare ECM sitting around in case you ever do wind up needing it. so not a bad idea to get one anyway.

for the coil and plug wires, im a bit at a loss, ive never seen a set of wires fail that fast, what brand were they????? ive always used AC Delco brand parts and never had a problem.

oh and by the way, welcome to the forum, im lovin the trend of ladies joinin the ranks

[grease monkey girl]

Thanks for the welcome
as far as the plugs and coil are concerned, we were blown away when we opened the hood and saw them sparking 24 hours after they were installed. The plugs are AC Delco, the coil is a different brand - I'd have to run out to the car to take a look. But the thing with the coil is this - the old coil was sparking, so we replaced it. The new one was sparking, so we thought we might have gotten a faulty one. We exchanged the part, put in another one, this one is sparking too, as are the plugs. I'm wondering if I have a serious electrical problem. I purchased the car less than a year ago, it appears that the previous owners didn't do as much maintenance on it as what should have been done. so I am concerned.
as far as the ECM, we priced those and they are not bad, but none of them have the EPROM in it. Any suggestions on where to find one?

[89IROC&RS]

hmmmm you very well might have an electrical problem, check the ground for the ignition system, ill check my shop manual sometime today if i get the chance, its an 89 camaro manual but shouldnt be much different as far as grounding locations for your 87. if the ground is bad, it may be sending excessive currant through the coil and wires causing your problem. by tryin to ground them to the engine and or other metal parts within shorting range.

as far as the EPROMs have you checkd Ebay for those?? if they arent there, hit up the local chevy parts counter, they can order them for you.

and sounds like your in the same boat i am, bought the IROC from a guy in arkansas, who bough it from some REAL shade tree mechanics, and have been fixing EVERYTHING on the car sense then lol.

[grease monkey girl]

lol yeah, there is a lot more work involved than what I was prepared for. The cars I had before were MUCH less complicated! But at least I am getting my mechanic training under my belt!
I did check on Ebay for the Eprom, I found chips, but do you think it would be wiser to buy just the EPROM or the ECM and EPROM?

[tacoma man.]

has any one suggested that it could be the transmission slipping? the clutches could be worn
out and slipping at high speeds.

[grease monkey girl]

well, now that it is in limp home mode, it's not doing the jiving anymore. I'm not sure if that's because we fixed the problem, then incurred a bigger one in the process.

[89IROC&RS]

ok, i really suggest the ICM now, its acting EXACTLY like my IROC was short of setting a code, which mine never did. its cheap, and really easy to replace. when i was at work, i used the TECH1 to put the car in limp home mode, and it ran much smoother, almost like it was supposed to run in regular mode. with the car in the driveway i started swapping ignition components between my iroc and my RS, nothing changed till i put the ICM from the RS into the IROC, made all the difference, still ran bad, cuz i had set the timing to the bad ICM and it is majorly advanced, but i think when i put a new module and set the timing to that, it will be running the way it should be. i think its only like 45 dollars brand new at the chevy dealership, at least for me, probly like 80 bucks for you, but im not sure. but try hitting up

www.gmpartsdirect.com

and see if they have a better price than the local dealership. from what youre describing, i really think thats your problm.

[grease monkey girl]

that would be heaven if that was the problem. I'll check it out.

[grease monkey girl]

oh, I forgot to say thank you!

[89IROC&RS]

yup, after shipping and handling its a little less than 44 bucks. from GM parts direct, at least for my 89 camaro. should be the same part number for your application, the PN is 10482827 use that for your search on GMpartsdirect, ill be checking at work to see what kinda price my dealership charges for it.

[89IROC&RS]

lol, your quite welcome. to replace it, undo the hold down screws on the distributor cap, pull it up and forward, you shouldnt have to pull any plug wires, the module is right there below the rotor, unplug the two connectors on the back, then undo the two small bolts holding it down, i used a 1/4 in driver and a 5mm???? socket to undo them. pull it back from the rotor shaft, there will be another two pin connector, disconnect that, and remove the old module. then simply do everything backwards to put the new one in. hope this helps.

oh and its not nessesary, but you really should disconnect the negative battery cable before servicing any module on the car. just to prevent electronic damage.

[grease monkey girl]

I'm sure it will help, thank you so much! I knew I came to the right place!