Bad ECU??

[highpsiguy]

I would appreciate any input on why my 87 GN seems to run in limp mode. Pretty much stock 19,000 mi car except for a TT Classic 5.7 chip. SCAN Master turns on and shuts off as seen in video. Car starts and then idles high with SERVICE ENGINE SOON light on. Thanks in advance

 

[mikestertwo]

Check your codes. Connect "A" to "B" on you ALDL connector, turn the key on and count the flashes on the check engine light.

 

[highpsiguy]

Check your codes. Connect "A" to "B" on you ALDL connector, turn the key on and count the flashes on the check engine light.

Ok, I just manually checked the codes using a jumper wire and the SERVICE ENGINE SOON stays steady lit.
TY

 

[TurboBuRick]

The scanmaster will show the code. Use the mode button. Keep pushing it till it say "MAL".

But first you need to figure out why there is no data on the scanmaster. Check wiring.

 

[Rick the pool guy]

When I watched your video I noticed you had no data coming into the scanmaster

 

[Rick the pool guy]

If you have no data coming in that's a Telltale sign of a bad eprom / chip I ran into this problem last year on an 87 GN

 

[salvageV6]

Unplug the ECM connectors IGN Key OFF, and then see if the light goes out with IGN Key in the ON position.

 

[highpsiguy]

Thank for the replies fellas! I remembered that when I purchased the car, it had a spare ECU in the trunk. So, I pulled the 2 chips from the installed ECU and placed them into the spare ECU. And guess what? The car started up and the Scanmaster displayed no codes!!
Now I need to find out why the ECU died...

 

[TurboBuRick]

Could have just been bad connections.

 

[highpsiguy]

I'm curious if there is a short somewhere that fried my ECU. I did have an old rusty relay that I removed. I think it was for the cooling fan. I don't recall reading anything related to the ECU that I could check. Does anyone have any suggestions, other tracing the harness to check for damage?
TIA

 

[salvageV6]

The bad connections are usually between the chip and chip socket or the socket and the ecm, or the main wire connectors and the ecm itself.

Look for corrosion and you can inspect the chip socket closely for bad or bent socket connectors the chip needs to make good contact to the socket metal tabs.

The original ECM may work fine with the chips re-seated and the main wiring connectors re-installed.

Then again most cars don't come with spare ECM's for no reason in the trunk....

 

[highpsiguy]

The bad connections are usually between the chip and chip socket or the socket and the ecm, or the main wire connectors and the ecm itself.

Look for corrosion and you can inspect the chip socket closely for bad or bent socket connectors the chip needs to make good contact to the socket metal tabs.

The original ECM may work fine with the chips re-seated and the main wiring connectors re-installed.

Then again most cars don't come with spare ECM's for no reason in the trunk....

Today I put my eprom / chip into the original ECU and it displayed the same issue as yesterday. So, I removed it and I put the eprom / chip into the spare ECU. I installed it and the car ran fine.
Thanks for the help. I just sent an email to Turbo Tweak to ask if they would test my ECU to determine what exactly failed. If I know that then maybe I can prevent it from happening again.

 

[highpsiguy]

The car backfired when starting, the had a misfire. I pulled the plugs, and since they were black, I replaced them with NGK UR4 plugs. I sent out the OEM injectors to Injector Rehab to determine if one was stuck open or leaking. They tested ok and were cleaned so I reinstalled them. The car started up but still has a misfire. I swapped the ECU out with another one that had come with the car and the "service engine" light lit up. My Scanmaster was blank.
If I were to install a known good ECU, where would I source one. Im unsure if the ECU, the Calpk, or the Prom is no good.
Thank you

 

[TurboTGuy]

Your in NYC? I have a known working spare I could lend you for testing, but I'm in Phoenix. You'd have to pay for the ride both ways.

Maybe there is someone local?

 

[highpsiguy]

Your in NYC? I have a known working spare I could lend you for testing, but I'm in Phoenix. You'd have to pay for the ride both ways.

Maybe there is someone local?

Thank you for the offer. Do you still have the Calpak inside of the ECU?

 

[TurboTGuy]

I might have one, but I would want that back, too, if I sent it.

You don't need the CalPac chip if you are running a Turbo Tweek Chip.

 

[dynoman]

Dave Husek is on Long Island and has a ton of parts , give him a call he might have one .
516-285-1103

 

[highpsiguy]

Im embarrassed to say that I had the spark plug wires for cylinders 2 and 4 mixed up. I corrected the mistake and the car runs smooth.
Thank you for your time and input Gents!

 

[TurboTGuy]

Good that you got it squared away!

 

[Anthony P]

I, too, will say kudos for figuring it out. And a plus that you used you original thread from 2019 to continue to conversation so the forum had the background info considering a limited use vehicle and so you didn't have to re-type it all.