'89TTA with 46k miles running rough

[dadsbad]

I've just acquired a very nice car that is completely stock and is running rough almost like it's out of balance until the r's get up to 2500-3000. Could this be the injectors, a bad vacuum line, or what?

[Sweet6]

When I bought my TTA with 39K on it, it idled pretty rough. I cleaned the injectors with the high pressure cleaner and it was better. I ended up buying new injectors anyway. I went with 50s and a turbo tweak chip since I was planning on upgrading the turbo anyway. It runs a lot better now. It still seems a little rough when cold.

[Lee_Burough]

Originally Posted by dadsbad

I've just acquired a very nice car that is completely stock and is running rough almost like it's out of balance until the r's get up to 2500-3000. Could this be the injectors, a bad vacuum line, or what?

A good place to start is with some data from a scan tool, you have one, yes?

I think you have to start from square one and go through a few things to make sure they are up to par. Scan tool data may focus your efforts right off. I'd start with A Spring Cleaning. (GNTTYPE.org is down for a few days, when its back up this link will work.)

Tap the MAF gently with a screw driver and see if it makes a difference in the idle....If yes, get a new MAF. Replace the fuel filter, check fuel pressure, check for vacuum leaks, check for air leaking into the Turbo inlet tubing starting with the air box, Put a big dose of Chevron Fuel System Cleaner through the tank, check the plugs, wires, coil and ignition....You'll probably find something to fix in that list.

Its normal for an LC2 engine to 'hunt' for the right RPM at idle (not 'miss'), that is, until you get a good modern chip in there. You need to confirm that the TPS and IAC are set exactly right too....

lee

[Sweet6]

If you are unsure of the history of the car, do the full spring cleaning. Most of those parts are cheap anyway. In general, I usually found running rough to be dirty injectors. Pouring cleaner in the tank usually does not work. But before you spend $100 getting the injectors cleaned, do all the other stuff first. Then if it still runs rough, consider gettting the injectors professionally cleaned or get new ones along with a new chip. I guess it will depend if you are planning on doing a mods to the car if you want to get bigger injectors.

[Lee_Burough]

Originally Posted by Sweet6

....Snip....Pouring cleaner in the tank usually does not work. .....

I agree. Thats why I recommended one of the only two products that really work through the tank. The other product is BG's K44, but it costs twice as much.

These two products (along with a carload of other fuel injector cleaners out there) were tested by a professional group specializing in fuels....they were the only two products that made a measurable difference. The product I recommended also works to remove carbon from your cylinders (reducing tendancy to predetonate).

If your problem is injectors, the best thing is new, flow matched injectors, The next best is to take your old ones out and have them cleaned, next is an injector cleaner through the fuel rail (a page dedicated to this procedure is on GNTTYPE.org), last is Chevron Fuel system or K-44 cleaner....The other cleaners are a waste of money.



I say the other fuel injector cleaners are a waste of money....I did have a Bronco II that responded well to CD-2 injector cleaner, but I can't find it any more.

[Sweet6]

True, some cleaners work and don't work. I would just think how about how much money you throw at stock injectors before you do it. My injectors needed the $100 full cleaning. I ended up picking up a brand new set of 50s for $250. So it was a no brainer for me.

[Kma697]

Got my TTA almost a year ago, like the others have said check for vacuum leaks, just get another set of injectors, definitely install a scanmaster or similar scantool because it will tell you where to start trying to fix the problems. Welcome aboard and enjoy the car, thats what we buy em for.
Listen to Lee he will point you in the right direction. Send your VIN to PHS and find out what number you have and never hurts to register it at TurboTransAm.com!!

[Lee_Burough]

One of my TTA's had been sitting a for a long time....It idled rough at first, but by the time I had driven it 1500 miles home and added the Techron, it was running a LOT better. Just driving it may help quite a bit.

[72firebird]

Originally Posted by Lee_Burough

A good place to start is with some data from a scan tool, you have one, yes?

I think you have to start from square one and go through a few things to make sure they are up to par. Scan tool data may focus your efforts right off. I'd start with A Spring Cleaning. (GNTTYPE.org is down for a few days, when its back up this link will work.)

Tap the MAF gently with a screw driver and see if it makes a difference in the idle....If yes, get a new MAF. Replace the fuel filter, check fuel pressure, check for vacuum leaks, check for air leaking into the Turbo inlet tubing starting with the air box, Put a big dose of Chevron Fuel System Cleaner through the tank, check the plugs, wires, coil and ignition....You'll probably find something to fix in that list.

Its normal for an LC2 engine to 'hunt' for the right RPM at idle (not 'miss'), that is, until you get a good modern chip in there. You need to confirm that the TPS and IAC are set exactly right too....

lee

I would follow these instructions. A scan tool is a must for any LC2 based car. Without having any data you're pretty much just going to end up throwing parts at the car and wasting money.