Jetta '89 random power loss

Hi everyone, i have Jetta '89 and i have problems with it. Car runs fine for a few days but then for some reason it looses power. Cars starts and they run ok but after every stop they loose power. When i push gas pedal gas stays on iddle fore some time and then car starts to move very slowly. Usually after about 4-5 sec the motor gets power and starts to run normally. The strange thing is that this doesnt happen all the time, for example when i went to service the car ran normally.:banghead:
The things i checked are:
MAF resistance - ok, moved cover and cleaned resistance plate, main and transfer pump works and everything else looks god.
This also happens more often when i switch AC on.
Any help is welcome.
Thanks.

I'd check the fuel filter and fuel pressure first. The possibilities that I can come up with are: the computer is going bad, Fuel issue (see beginning), or the air flow sensor isn't working correctly. I'd want to check the fuel supply pump (in the trunk). When it fails it behaves like you've described. When the main fuel pump goes, you can floor it, but it acts like the accelerator is barely pushed.

I'd check the fuel filter and fuel pressure first. The possibilities that I can come up with are: the computer is going bad, Fuel issue (see beginning), or the air flow sensor isn't working correctly. I'd want to check the fuel supply pump (in the trunk). When it fails it behaves like you've described. When the main fuel pump goes, you can floor it, but it acts like the accelerator is barely pushed.

The fuel filter is new and i dont have equipment to check fuel pressure. I checked air flow sensor and it looks god but i cant be sure, dont know about the coomputer. I'll change the computer and sensor so i'll know if they were the problem. I also checked fuel pumps and they work.
Thanks.

Let's try the obvious. Look for vacuum leaks and check your air filter. I've had rain get sucked up onto mine before and it caused intermittent failures. With fuel injection, the throttle opens airflow, the MAF should sense it and the computer should tell it to send more fuel through the injectors. Fuel pressure gages cost about $20 at auto parts stores. They can be really useful for narrowing down problems. It sounds like something electrical. If you have to replace the computer check ebay first, you can save a lot for this type item.

I've been having the same issue with my '89 Jetta for about the past 4 months, eventually it got to the point where I couldn't actually keep the car running for more than 30 seconds. I had it towed to my mechanic and it turns out that my distributor cap was completely melted/broken. When we went to buy a new one the guy at the parts store and my mechanic was surprised it ran for so long. I (of course) had problems getting the car started a lot of the time. My mother took the car for a nice long test run today and while it didn't idle out and die on her, she said that it did start to hesitate a bit, but didn't idle out (die), so I'm not sure if it's the same kind of thing as before we replaced the cap (doesn't sound like it though, because it didn't outright die).

Let's try the obvious. Look for vacuum leaks and check your air filter. I've had rain get sucked up onto mine before and it caused intermittent failures. With fuel injection, the throttle opens airflow, the MAF should sense it and the computer should tell it to send more fuel through the injectors. Fuel pressure gages cost about $20 at auto parts stores. They can be really useful for narrowing down problems. It sounds like something electrical. If you have to replace the computer check ebay first, you can save a lot for this type item.
I checked ecu connector according to Bentley service manual, everything is ok.Visualy checked ecu - opened to se inside - everything looks ok.Fuel pressure is OK only after engine off and one minute there is no residual pressure.Coolant temperature sensor haw incorrect resistance so I have to change it.Air filter is new.When I tested car they started and work correct on iddle but when I tried to drive they start very slowly.

I've been having the same issue with my '89 Jetta for about the past 4 months, eventually it got to the point where I couldn't actually keep the car running for more than 30 seconds. I had it towed to my mechanic and it turns out that my distributor cap was completely melted/broken. When we went to buy a new one the guy at the parts store and my mechanic was surprised it ran for so long. I (of course) had problems getting the car started a lot of the time. My mother took the car for a nice long test run today and while it didn't idle out and die on her, she said that it did start to hesitate a bit, but didn't idle out (die), so I'm not sure if it's the same kind of thing as before we replaced the cap (doesn't sound like it though, because it didn't outright die).
Distributor is not original so I have to buy cap according to PN on it.

I don't want to beat a dead horse, but I'd have the fuel pressure checked to ensure you have 40 + psi. It sounds like it's not getting gas. So either it's not telling the fuel injectors to open, the fuel injectors are clogged, or there isn't sufficient fuel pressure. If the MAF sensor isn't working right then it can't tell the throttle is opened. If the pressure is low, not enough fuel will pump. If the injectors are clogged, not enough fuel will enter the cylinders. The only thing I can see that you haven't mentioned is checking your fuel injectors. You may try some SeaFoam or other injector cleaner.

I don't want to beat a dead horse, but I'd have the fuel pressure checked to ensure you have 40 + psi. It sounds like it's not getting gas. So either it's not telling the fuel injectors to open, the fuel injectors are clogged, or there isn't sufficient fuel pressure. If the MAF sensor isn't working right then it can't tell the throttle is opened. If the pressure is low, not enough fuel will pump. If the injectors are clogged, not enough fuel will enter the cylinders. The only thing I can see that you haven't mentioned is checking your fuel injectors. You may try some SeaFoam or other injector cleaner.
When start engine and allow it to idle, fuel pressure was 2.75 bars.
I know that for car moving there is two thinks that they need.
One is fuel and other is voltage.In this moment I check fuel.
When you switch AC on who is responsible to maintain correct throttle.
I will remove ISV and clean it – what you thing that is better to use, WD – 40 or carbon cleaner
If I remove fuel injectors do I need to changes seals-o rings?
According to Bentley Manual I was check AFS – resistance between terminal 2 and 3 should vary as the flap is moved. This information is not correct because you have to move flap very very slowly and resistance must change continually up and down.When I do this test again resistance vary but not continualy.Then I removed AFS from car,removed plastic cover from potentiometer housing .
I found that slider lose good contact on hole length of main resistor and made groove. Disassembly slider, potentiometer plate, connector but didn’t touch return spring .Clean contact on slider with fine send paper, clean potentiometer plate with alcohol. When assembly plate I slide it toward the connector – whole allowed this. Now slider have different path and when I test resistance I got continually change. On slider is screw which allowed to change it start position and got more fuel on idle.
To remove plate you don’t need to disassembly slider, only unscrew little beat screw and push plate.
Now I wait for Saturday and Sunday to continuing with car repair.

I just got word back from my mechanic that my airflow sensor was acting up and that it had become loose, therefore sending incorrect reading to the-whatever-the-readings-are-sent-to, but this ended up causing a fuel/air mixture which was actually much too low for what the car actually needed (vesus what the sensor read) and that caused my '89 Jetta to randomly lose power.

Thanks, first think what I checked when tried to repair my car was AFS.This unit is very sensitive again air moving and also again vibration .In this moment I think that this unit work good .Problem with my car is that they one day work normally –another problem.