WTF!! Is my car bipolar??

[MR2CHIPO]

Hey guys!

I just got my 84 rebuilt and it has new plugs,coil, plug wires, fuel pump, 42injectors with TT chip, etc. Problem is it idles perfectly for a while,then it starts sputtering and idling VERY rough. Black smoke everywhere and scanner reads overboost.....while at idle!! Something is causing it to open up the injectors as if at WOT. Crazy thing, I'll shut it off, then it'll idle beautifully.....for a little while at least :-( Any help would be greatly appreciated

p.s
looked for vacuum leaks, didn't find any

Cesar

 

[esinger]

Do you have any idea if this is occurring when the car goes into closed loop? If so it maybe a bad O2 sensor.

What kind of scantool are you using??

 

[boostmaster]

Do you have any idea if this is occurring when the car goes into closed loop? If so it maybe a bad O2 sensor.

What kind of scantool are you using??

Nah, don't think it's the O2. either bad ECM or bad maf (air flow) sensor. Swap the maf with a known good one or when it starts acting up tap on it. Also it will probably be a good idea to go to the auto parts store and get you some CRC Maf sensor cleaner. That exact brand and follow the directions, that stuff works!!!

 

[MR2CHIPO]

Scanned using a snap on scanner at my buddys shop. Have used a different ecm w/ same problem. Will try cleaning maf as I don't have access to known working unit. Thx for the suggestions

 

[esinger]

Yeah, MAF was my next guess. Are you running the 86/87 ECM or the orignal 84/85 ECM with the TT chip? Just want to get the depth of your changes because it may not be any of the sensors.

 

[MR2CHIPO]

using 84/85 ecm

 

[esinger]

Good luck! 84/85 MAF sensors aren't the easiest things to come by. I was just checking to see if you're running an 86/87 ECM with a 84/85 MAF.

 

[fmster]

using 84/85 ecm

Where are you located? I have a good maf,it has no screen on it.

 

[MR2CHIPO]

Kissimmee

 

[boostmaster]

Where are you located? I have a good maf,it has no screen on it.

If it doesn't have a screen in it it's not a good maf!!!!! The chips are calibrated for maf sensors with screens otherwise you'll get the same rich fuel mixture condidtion. I thought you wanted to find problem? If your throwing questionable parts at a problem then how do you expect to find a solution? Your vehicles ECM is a accurately claibrated instrument and it only can command certain actions based on the input of certain components, sooooo the general rule of thumb is "junk in = junk out"......GOT THAT? Your wasting all this time and effort at the expense of what, a 10.00 can of maf cleaner? Maybe it's not the problem but for only 10.00 and a solution now I think it's worth a try. Or you can ride all over Fla looking for a maf sensor or pay to have used one shipped that might be good. Point is if it's not on a running car or a car that I removed it from and I can't verify it, I don't know if it's a working unit or not.

 

[turbo6x2]

An 84-85 maf is very expensive and it this the issue you might want to consider to the conversion, I would also ask are you still running a stock 84-85 ecm cause these had problems as well. If this is bad you may want to consider switching to an 86-87, more reliable and a better ecm since it can log more data. I would go with bad maf from what you have described.

 

[BRAD_PADGETT]

using 84/85 ecm

I will tell you like it is. If you plan on keeping your car the following have to be eliminated and replaced-84/85:MAF, ECM, chip, coil module and coil pak. Replace them with the following:86/87: ECM, chip, coil module and coil pak. The MAF should be an LT1 with a translator. The stock 84-87 MAF are too old, out of production and the remans don't work. Anything less than this is really just screwing around, beating your head against the wall and a car that runs like crap. My 2 cents. Brad

 

[fmster]

If it doesn't have a screen in it it's not a good maf!!!!! The chips are calibrated for maf sensors with screens otherwise you'll get the same rich fuel mixture condidtion. I thought you wanted to find problem? If your throwing questionable parts at a problem then how do you expect to find a solution? Your vehicles ECM is a accurately claibrated instrument and it only can command certain actions based on the input of certain components, sooooo the general rule of thumb is "junk in = junk out"......GOT THAT? Your wasting all this time and effort at the expense of what, a 10.00 can of maf cleaner? Maybe it's not the problem but for only 10.00 and a solution now I think it's worth a try. Or you can ride all over Fla looking for a maf sensor or pay to have used one shipped that might be good. Point is if it's not on a running car or a car that I removed it from and I can't verify it, I don't know if it's a working unit or not.

It was a FREE part he was getting!!!!!!!!!!

 

[boostmaster]

It was a FREE part he was getting!!!!!!!!!!

Free part= maybe burn 10.00 worth of gas to pick it up or ship a possible bad unit. Maf cleaner= 10.00 or less might solve the problem, go figure.

 

[turbo6x2]

Generally speaking once a MAF bites the dust all the cleaner in the world is not going to help it, just my two cents from past experience.

 

[MR2CHIPO]

Guys!
Want to thank everyone for your input. Haven't has internet access for a few days, thus no prior replies. Thinkink maf upgrade w/ translator might be best option as i plan on keeping car. Already hace upgraded coil,module with 86/87 pieces. Will need ecm upgrade. Best maf option ideas?

 

[novaderrik]

check the wires going to the temp sending unit in the intake manifold. if they short together, it will always think the engine is dead cold.
on my car, the insulation on the wires shrunk back about 1/4" from where the wire goes into the plug and the wires would come in contact if the engine vibrated just right. a little bit of that electrical wrap that sticks to itself fixed that problem for me 5 years ago and it's still holding up.

 

[MR2CHIPO]

Have replaced ecu with an 86/87 unit and no improvement. Guess is on to the lt1 maf and translator........