gleamingred944

I've got a problem with my '86 n/a. It's running fine every other way, but when I press the accelerator the last inch, the power cuts out, totally. If I lift the pedal that inch, power is instantly restored. Of course I only do that when the RPM is above 2000, and when the engine is fairly near operating temperature, but it seems to happen no matter what the RPM or temperature. (No, I Won't do it when the block is 20 below or RPM is at idle!)

The only thing I can find wrong is that the air temperature sensor that's mounted on the thermostat housing seems to be locked on. I realise that when a detail is wrong, fix it, but I suspect that something else might be out of kilter as well.

Any suggestions?

SoCal Driver

Three temp sensors. One in the AFS. Two on the block; one for the DME and one for the temp gauge. Don't know of any in/on the thermostat housing (water pump).

Could have the throttle position switch set wrong. It's the black box on the throttle body. This has to be set so that it clicks just as the throttle is closed.

Also thinking AFS, fuel pressure/delivery.

Yabo

hey, same problem i am having pretty much. (how come nooone remembers) it could be the airflow meter... im replacing my ignition system (besides teh coil) to make sure its not that. I dont think its my tps.. because it only happens at 3000 rpm and up.

ilikemy944

I have $1 on the tps.

inactiveuser92616

sounds like the TPS is busted or miscalibrated. The DME control unit is programmed towhere at fully closed throttle, above (2000?)RPM it cuts fuel. This is simply to save fuel when you are coasting. Sounds to me like it is somehow now triggering at wide open throttle rather than fully closed throttle, for some reason.

gleamingred944

Many thanks, all - checked the TPS and it seems to be OK, so I'll try the AFM next. It won't be a quick fix because I have to wait until a friend is free who's better at mechanical things than I am. That's a tricky box.

SoCal Driver is right - the sensor I'm worried about is in the AFM. Gee, there are a lot of wires in our cars!

Yabo

Question about the tps. I get the click at the closed throttle. but at full throttle, no click. woudl that be adjustment? or woudl that be dead tps? whcih way do i need to adjust it?
thanks.

SoCal Driver

TPS full throttle cuts the Ox sensor out. Closed throttle cuts the fuel off until the engine rpm's drop below 1400 or 1600. The injectors come back on line when the engine rpm's reach idle. When these rpm settings are off you can ge an rpm occilation as the logic bounces between high and low rpm's.

Check out http://www.frwilk.com/944dme

Yabo

anyone got an answer for my tps question? if socal had the answer, i dont really unerstand.. is mine dead or need adjustment probably?

SoCal Driver

Should have a noticeable click when the throttle closes. This does not mean that the contacts are closing. Have to use an ohm meter on the plug pins.

Full throttle may or may not have a noticeable click. Again you have to use and ohm meter. However full throttle is not anywhere as important as closed throttle.

Go to Wilk's web site and read the part about the throttle posisiton switch. He has found that some of the early DME's had a programming error that changed the related rpm cut off and start values. He sell a chip specific to correct this problem.

Peckster

I very much doubt it's your ignition system. It's related to the position of your throttle, so it's something in that area. Operate it by hand and see if you can see something touching or binding.

SoCal Driver

Once you clear the TPS then I would take a serious look at the AFS. Put an ohm meter to the pins and see if the resistance is linier as you move the flap. No dead spots.

Skip

The TPS is a single failure unit - it "shouldn't" ever effect cutout. The switch is for Idle only. That said, I think there have been reports here over the years that it was in fact the TPS (or, replacing the TPS fixed the problem... ya never know what else got "bumped")

Internally, the AFM "wiper" and trace can be cleaned (of carbon) with a pencil eraser or alcohol damped Q-tip. Could also be a vacuum/intake leak - those sometimes only show up at high rpm's.

Good Luck!

mossy

Gotta be the TPS, switch failure causes some wierd stuff.....
There's a useful replacement (adjustment) procedure here:
http://www.clarks-garage.com/
Good luck

Yabo

i thought high rpms was a low vaccum state.. and idle a high one, so you would notice vacuum leaks at low rpm?