service engine light flickers

[Daniel Doutt]

My service engine light flickers. replaced o2 sensor, fuel filter, maf,new plugs and wires. As soon as you turn key on engine not running the light comes on solid of a second the starts flickering . car runs like its on 5 cyclinders.
Its a 1987 buick gn. think maybe the computers bad. any suggesions

 

[85typet]

my car does the same thing and when you give it gas it runs fine but when idleling it kind of has a slight stumble to it

 

[Nascar83Fan]

Hey i had a similiar situation, which turned out to be nothing more than the nuts on the ICM bolts that held the ICM to the mounting plate had came loose that it wasnt getting a good ground which was causing it to throw a code 42 and she coughed & sputtered cause of the poor ground messing with the spark timing under acceleration cause the engine was tossing the ICM alittle under acceleration. As soon as i tightened down the nuts and fired her up no more code & she's been running on all 6 since then. At first i thought maybe my ICM or the coil pack was going out, but it was a simple fix that cured my problem. I have an 87 Turbo T and she's a daily driver for me. Try checking for loose grounds, having a scanmaster does make it easier to chase down where the problem lies. Hope that helps

 

[RmvBfrFlght]

My service engine light flickers. replaced o2 sensor, fuel filter, maf,new plugs and wires. As soon as you turn key on engine not running the light comes on solid of a second the starts flickering . car runs like its on 5 cyclinders.
Its a 1987 buick gn. think maybe the computers bad. any suggesions

A fast flashing SES means that the ECM is in limp mode. Due to the EPROM check-sum or check-bytes being incorrect. That is, the ECM believes that the 'chip' is corrupt. This can be caused by several factors:

The ECM is bad, the EPROM is bad, or the socket to pin contact for the EPROM is bad. For the last issue can many times pull the EPROM out and using a small pick bend the ECM socket contacts for better connectivity.

You shouldn't really drive the car with the ECM in limp mode. More so if the engine/injectors/etc. have been modified.

First thing to try is to remove the EPROM and re-install it. This 'wipes' the socket to EPROM pins together and may be enough to get good contact.

RemoveBeforeFlight

 

[turbo2nr]

SES light with FAST system?

It is annoying to me. Why is it on?

Easiest way to stop it?

I have a feeling I am going to end up tear apart my dash and yank out the light-bulb?

Any other easy way?

Scott

 

[Razor]

SES light with FAST system?

It is annoying to me. Why is it on?

Easiest way to stop it?

I have a feeling I am going to end up tear apart my dash and yank out the light-bulb?

Any other easy way?

Scott

Read the code.. eliminate the issue.. problem fixed.

Reminds of the 80's when engine light would come on.. put black tape over the bulb.

 

[Nascar83Fan]

Even bone stock these cars can be finicky, throw in mods and just makes them even more tempermental. Choose your upgrades carefully and be even more careful of who does the work, these engines can in less than a blink of an eye can go from running to hand grenade with one little mistake.
Ignoring the SES on these cars is asking to have big repair bills sooner than later, they arent the run of the mill small blocks or big blocks you could maybe get away with ignoring the SES light or tape electrical tape over it. Something isnt right and the car is trying to tell you something needs fixed. Get a obd 1 code reader / scanner to pin point what code(s) are being thrown if you don't have a scanmaster installed, although having a scanmaster is pretty much a requirement to have in these cars to keep tabs on things and make life alittle easier if you start having codes thrown to cycle thru to see any mal codes.


Posted from the TurboBuick.Com mobile app

 

[turbo2nr]

The stock ECU is not doing anything. (I thought?)

Engine fuel/spark is all done by FAST system.

Who cares what code? I thought the stock ECU wasn't even hooked up anymore?

How does it even know the engine is running for that matter? LOL

The car is new for me and I have not bothered to tear into stuff just yet.

 

[Razor]

The stock ECU is not doing anything. (I thought?)

Engine fuel/spark is all done by FAST system.

Who cares what code? I thought the stock ECU wasn't even hooked up anymore?

How does it even know the engine is running for that matter? LOL

The car is new for me and I have not bothered to tear into stuff just yet.

The XFI(FAST) uses the check engine light to show you there is a trouble.. like a map-adjusted TPS, or wideband going out.. You need to read the code while the Key is ON.. and light shows red.

 

[Razor]

Contact who tuned the car for help with the XFI or read its help section/

 

[turbo2nr]

Thanks for the reply.

Have not had time to download the FAST software and go thru it all.

Been Seven years since I had a FAST System, and I sold the car right after due to getting frustrated with a certain vendor.

Car was a total loss for me.

So, Read code from FAST unit, or regular method? I guess from the FAST unit via laptop?

 

[Razor]

If its an XFI,
Connect to unit.. F9 will pull up the screen.. you'll see the error code 1 and error code 2.
Go to the help section under diagnostics and see what the code means.
Once you shut the KEY off and the unit fully powers down.. you lose the code. Thats why you need to read it while the light is lit.
What I do is shut the key off and quickly back ON.. this keeps the code while I go get the laptop and go through the paces.

 

[turbo2nr]

Thanks!! Yes, is XFI unit.

The SES is not on today....just saw it On briefly a day or two ago.

Car runs great! Only taken to 1/2 throttle until I am familiar with everything.

Scotty