After spending countless hours on trying to figure out why my 89 TA runs like sh*t after it gets warm, I have reason to believe that it might be the MAF sensor. I just want to confirm with someone before I spend $$ on a new one.

With the iginition ON and the engine NOT running, I have 0VDC coming from the dark blue (burn off) wire, 8VDC from the dark green (signal wire) and 0VDC coming from the red wire.

I've tried unplugging the MAF after the car acts up, but it doesn't seem to run any better or worse. I have not tried tapping on it yet. Anyway, any thoughts on whether I'm on the right track or anything else I can check before replacing it. Thanks!

 

Anybody???

 

Have you checked the Ignition module...Inside the distributor .!! (warm sensitive)

Try the theory , (with the maf being bad ) , to get it warm by using a Hot air gun before the motor starts to build up heat...

 

Describe your PCV system IN DETAIL.

 

Sorry, what is pcv?

 

pcv=positive crankcase ventilation, on one of these cars it normally consists of a pcv valve in one valve cover with a vaccum hose going to it, on the other valve cover would be a breather, or a hose that feeds into the air cleaner to a filtering element to provide clean air to be drawn through the crankcase via the pcv valve. I think I see where sofa is going with this but I'll leave that up to him..

 

Yup, you probably do, since it's a MAF car.....

 

I'd have to look at it to describe the pcv in detail, but nothing has been done to it. The car is pretty much stock. The first thing I checked were hoses to see if there was a vacum leak somewhere, but everything looks pretty good. Is there something in particular I should look for? I'm curious where you are going with this.....

 

It's a MAF car.

That means, the Mass Air-Flow sensor has the job of measuring the amount of air entering the engine and passing that info to the ECM, so that the ECM will know how much fuel to put in.

If ANY air gets into the intake that hasn't passed through the MAF, the ECM won't know that it's there, and won't meter fuel to go with it. Extra air without fuel = a lean condition ("lean" being the word we usually use to describe "not enough fuel for the amount of air"). A lean condition will lead to all sorts of driveability problems; rough or irregular idle, unstable idle speed, bucking and surging while cruising, coughing and sputtering and hesitating when accelearting or even backfiring into the intake, and so on. The ECM uses 2 different fuel tables, one for cold start-up operation, and one that's much more tightly controlled for warmed-up operation. So typically, the motor will run OK, if maybe not perfect, when cold; but will descend into lean hell when the temp gets to normal.

Sound familiar?

The PCV system offers a way for air to get into the engine WITHOUT passing through the MAF. Note that there are 2 hoses that come off the throttle body and go to the valve covers; one goes to the driver's side and has the PCV valve in it, the other goes to the pass side. The PCV valve draws air into the intake. The other hose provides air to go into the crankcase to replace the air that the PCV valve lets into the intake. The point at which that hose is hooked to the throttle body, is UPSTREAM of the throttle blades themselves, but DOWNSTREAM of the MAF: in other words, the air that goes that way will have already been through the MAF, been measured, and the ECM will know about it so that it can supply fuel to go along with it. If that other hose is not there, for example if it has been replaced by one of those stupid "breathers" that pukes oil all over the valve cover, then whatever air comes into the intake via the PCV valve WILL NOT have passed through the MAF (because it came in through the stupid "breather" instead), the ECM WON'T know it's there, consequently it WON'T supply fuel for it, and you'll have this terrible lean condition.

Describe your PCV system IN DETAIL. Are BOTH hoses there, hooked up, intact, going to the places they belong going? Then look VERY CAREFULLY at the entire intake tract. Are there ANY leaks between the MAF and the throttle body? loose hose clamps? cracks or holes in that little bellows hose? etc.

 

Thanks for your detailed response. Sorry for the detailed response, but I looked very carefully at the pcv and noticed the following:

• There are two hoses coming off the passenger side of the throttle body.
• The larger of those two hoses goes directly into the passenger side valve cover
• The smaller goes to a black cylinder located right beside the air filter canister
• There is another hose that goes directly from the driver side valve cover to the intake
• There is a very small hose that comes out of the bottom of the throttle body and runs right beside the EGR valve and fuel pressure regulator. That hose terminates at a very small black box that is towards the pasasenger side of the distributor. I'm not sure what it is or what it does.

All of these hoses look to be in good shape. I went over the entire air intake and there are no holes. What you're saying makes complete sense to me and definitely describes the problem I'm having, but everything looks stock. No hoses were replaced or changed and this problem came out of no where. I drove the for over an hour, ran fine and the next day it starting acting up. The one thing I did notice is that the fitting between both hoses that go into the valve covers seem to be very loose. They pull out very easily. Anyway I hope this helps explain things on my end a little better. I am getting a MAF High code (33) through tunerpro. I'm not sure if that sheds any light on this subject. Any thoughts where to go or what to try? Again, thanks for taking the time to help me!!

 

Anything?