Help, I have been trying to diagnose a problem with my 87 305 tpi bird since after a year of sitting due to a bad fuel pump.

I replaced the fuel pump/filter. I removed the fuel rail and visually watched the injectors spray.. all is fine.

Replaced the distributor, rotor , & cap.

Symptoms with MAF & tps connected:
Car runs very rough and is sluggish upon accell. It will start and idle after a few start stall attempts. It can't seem to idle correctly (varies from 500 - 800 rps), and if you try to take it out of park or neutral it stalls almost immediately.
Will throw a code 34 (MAF) if the maf is connected. IF you disconnect the maf I get a code 33. IF you connect the MAF and disconnect tps there is no change.


Ok now comes the funny part
IF I DISCONNECT the MAF and TPS at the same time
*Idle is stable at about 1500 rpms. (not rough .. no more shaking of the car/engine) if you I try to accell it seems to smoothly until the air/fuel ratio goes out of wack and rpms fall (due to no throttle imput to ecm).
*if I put the car into reverse it does't stall or buck.. runs smooth as it should?

Any ideas whats going on here.. Im about the sell the car and know it worth way more money if i can showcase how nice the engine runs (well ran).

Please help ...

 

I plan on testing my tps sensor tomorrow per the tech articles.

Is there any way to test maf .. autozone?

 

just for the hell of it, check the ohms on the injectors, both hot and cold. When we flow the stock injectors on static, 99% of the time they flow just fine. Once they start going through the various duty cycles we find that the coil shuts down. Just a thought.

 

A bad MAF code isn't a good sign. Test the TPS first, as you plan to. If it checks out OK, you might be looking at a new MAF sensor.

If, however, the TPS checks out bad (fairly common problem on the old TPS sensors) replace and adjust it first- it's a lot cheaper than a new MAF and might just make the MAF code go away (longshot, but possible). Those early TPS sensors have an adjustment procedure to get the idle and WOT voltage correct. Basically loosening the retaining screws and moving/rotating the TPS around slightly. The idle (closed throttle voltage) is the most critical. I think spec is something like .6V, but you can check the thech articles for the right number. The WOT voltage is less critical- anything over 4V the ECM interprets as "wide open."

 

Some more info on the maf code... I have had intermittent maf codes since I put a DIY cold air intake system in the car about 10 years ago.. It always ran fine and I have always disregarded these codes until now. But it does seem odd that the performance only improves if I disconnect both sensors at the same time... Either one disconnected independently of the other does nothing. I will be testing the tps in the few min. and Ill post the results

 

TPS tested ok .5 v at idle 4 volts a WOT .. linear increase in between..

I took a shot in the dark and replace the IAC and cleaned the thrttle body.. (no change)

So currently as it sits .. with the MAF plugged in the car stalls and is very sluggish on accel,
if the MAF is unplugged the car seems to have a responsive accel (like normal) but really can't idle ... stalls out most of the time... idles between 500 -1000 rpms jumping constantly when its not stalling..

if is disconnect TPS and MAF car idles smoothly (this is why I don't think its a vacuum leak) although the idle speed increases to over 1000 (1200-1400) rpm .. I believe it used to idle at 750 -800 rpms ; but if you try to accell it stalls (because the computer doesn't know im opening the throttle and so doesn't correct the A/F ratio.

Its obivious I'd love to try an other maf .. but I just don't have the money to spend unless im positive that it will fix this idle/performance problem.
Should the car be able to idle properly(smoothly - no jumping) with the MAF disconnected? if so then I guess vacuum or O2 sensor are the only other things i could think of? Help

 

Also one more note on the MAF the air filter was extremely dirty (like 90+ blocked) which could very easily have caused a code 34 (low air flow throught maf).. Unfortuntaly removing the air cleaner once again doesn't change the symptoms of the rough idle/stalling problem (even w/ them maf disconnected)

 

Can someone with a similar working TA w/ a tpi setup please disconnect your maf and tell me if your car will idle.. I'm trying to trouble shoot and do not have the money to throw at the maf if it isn't going to fix this problem ...

 

I did that exact test years ago on an 87 L98 TPI. It idled and ran OK. Obviously, the check engine light was on solid, but it would idle and drive acceptably.

 

I have a 90 formula 305 similar problem have a code 22 and a 33 car will start and barely idle withe tps hooked up when unplugged runs better but upon acelleration dies has no power under load

 

yeah i should have mentioned its tpi fuel pump filter injectors rail regulator map sensor plugs wires all good