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89 GL10 Turbo acceleration hesistation w/ turbo


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I had an earlier thread with problems with hesitations (2 every second or so) when the turbo kicked in during acceleration. Checked throttle position sensor, o2 sensor, plugs/cap/lines, all other lines, air filter, vacuum leak,ignition coil, timing and have now changed the fuel filter with no luck.

My mech was still thinking that the straight pipe I have may possibly be involved with the exaust leaving at an uncontrolled rate. I'm going to put on an XT exaust / tail pipe set up anyways because my ears ring after going downhill in gear and it may make diagnosing a little easier when you can hear the engine a little more properly. That's my own totally uneducated theory. I'll update with any info as it appears to be a not too uncommon issue. Do many other people with EA82 engines encounter this at all?

 

simon

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Exhaust flow issue? I doubt it but why not do the swap just to rule it out.

This problem has pissed me off more days than i care to remember

I've had three ea82t wagons and all had this problem. disconnect the engine coolant temp sensor connector off of the thermistor that threads into the coolant port on the intake see if that "fixes the problem" . This puts the car into limp mode,less sensors are factored into the air fuel ratio.

On the one car this little unit was the problem, something to do with the air fuel ratio being affected from the bad output to the computer. I think you can check the reisistance in place.

On my 3rd wagon, the one in the sig., the hesitation was more pronounced when i installed the manual trannie. I still haven't dealt with the issue i just drive around with the coolant temp sensor disconnected. I don't know if that helps.

I guess if it runs better in limp mode you'll know that it is sensor related and not exhaust. :)

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Yup, happens with my 86. I attribute it to a possible alt/voltage descrepency. When the injectors dont get a steady voltage, they will not pulse correctly. When I get a new(er) alt hopefully this will cease. A weak coil also might contribute to this symptom.

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Mmmm, thanks for the thoughts. I'll give those a try. Nice to know that I'm not the only one that is experiencing this. Personally, it makes me mental when it happens. It's like having a sort-of-turbo. Hey Vanislru, that's interesting that you got the problem when you put in the manual trannie as this car has gone from auto to manual. Some weird incompatibility with some sensors btw man and auto?

 

Simon

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I checked for vaccum leaks and found none. The problem was more noticeable with the manual trannie i think because their is no torque converter to absorb the inconsistancies in the torque curve.

Jazzician did you try to unplug the coolant sensor connector?

If you take off the turbo intake piece you can gain easier access then it's just a matter of removing the little wire holding clip that keeps the connector in place.

Check it out you'll know if it;'s a sensor prob.

I had this problem when it was an atuo too.

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FWIW, I have a connection problem at my CTS. Going down the road the connection (or defective CTS? been replaced...) goes wonky for a second and the car shudders and the CEL blinks on and off. Real pain. Almost makes me want to cutoff CTS connector and rewire it. Almost...

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It's interesting that you mentioned the Engine Coolant Temp Sensor. I don't know if this is related, but I have noticed that it is much more pronounced when I have been driving for a little bit. When I first start up the car, I really don't notice it.

 

Exhaust flow issue? I doubt it but why not do the swap just to rule it out.

This problem has pissed me off more days than i care to remember

I've had three ea82t wagons and all had this problem. disconnect the engine coolant temp sensor connector off of the thermistor that threads into the coolant port on the intake see if that "fixes the problem" . This puts the car into limp mode,less sensors are factored into the air fuel ratio.

On the one car this little unit was the problem, something to do with the air fuel ratio being affected from the bad output to the computer. I think you can check the reisistance in place.

On my 3rd wagon, the one in the sig., the hesitation was more pronounced when i installed the manual trannie. I still haven't dealt with the issue i just drive around with the coolant temp sensor disconnected. I don't know if that helps.

I guess if it runs better in limp mode you'll know that it is sensor related and not exhaust. :)

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the exhaust system has nothing to do with it. I can tell you that much. turbo cars like to breath free. no restriction needed.

 

some things to think about.

 

yes temp sensors can be troublesome. driving with it disconnected is just as bad for the car as with a bad connection(or sensor) there.

 

so mabey I missed it but did you check fuel pressure under boost?

 

it still sounds rather igniton like. I know you have swaped out a ton of parts it seems but there is a transistor on the coil bracket that actually does the switching for the coil. might be something to keep in mind.

 

wait I just reread it. you checked the plug wires ect? how? under load?

or was it just a visual inspection? I thought they had been changed.

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collant temp sensor has a very large part in how the ecu meters fuel

when the motors cold it adds more to compensate for that

so if you ahve a bad sensor or a crappy connection then its going to think the motor is cold add excess fuel ect ect

 

how much does the cts affect how a fuel injection ecu runs...

well when i did my ms swap i accidently wired the cts wire to the knock sensor.. oops to many wires lol so my ms was showing the motor to be at like -140degf and inturn was just dumping so much fuel into the motor it would hardly run if at all i couldn't even detune the injection enough to compensate for it

 

try grounding your cts wire out.. the ecu will go absolutly nuts and the car will run like crap if it will run at all

 

needless to say i felt really stupid :)

 

but check the connection or replace the sensor is my vote

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I suggested disconecting it [the cts] strictly for the purpose of ruling it out and putting the car into limp mode. If the car runs better in limp mode then you will know it's sensor related. This doesn't mean that it is the cts, it could be any of the sensors the computer 'ignores' while in limp mode. These things do cause alot of problems all on thier own though.

 

I ran the previous car for 9000km or 5500mi. without the cts. connected. It runs rich and makes the plugs a little ugly, at the time it was better than jerkin all over the mf'n road. Harmfull, uh maybe to air quality but to the engine? It's been my experience that these motors can run a long time in limp mode with no real issues. :)

 

I replaced the cts with a new oem sensor and the car definately has less hesitation, I also pulled the disty out and cleaned with brake cleaner and then lubed it. Now the vac advance mechanism moves nice and easy. No noticeable hesitation. :grin:

Sensor should be about 27 cdn from subaru guys.

 

Good luck.

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the exhaust system has nothing to do with it. I can tell you that much. turbo cars like to breath free. no restriction needed.

 

some things to think about.

 

yes temp sensors can be troublesome. driving with it disconnected is just as bad for the car as with a bad connection(or sensor) there.

 

so mabey I missed it but did you check fuel pressure under boost?

 

it still sounds rather igniton like. I know you have swaped out a ton of parts it seems but there is a transistor on the coil bracket that actually does the switching for the coil. might be something to keep in mind.

 

wait I just reread it. you checked the plug wires ect? how? under load?

or was it just a visual inspection? I thought they had been changed.

 

Yah, plugs wires, cap and plugs and ignition coil were changed

I'll look into if we check fuel pressure under boost.

I'll also check the transistor on the coil bracket. I assume it is separate from the ignition coil?

Also checking the alternator as well. We also checked for voltage changes throughout the system to see if there were any differences.

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I've been reading all these posts about this rythmic "hesitaion" while the turbo is kicked in because I have just aquired a 1985 turbo wagon and it does the same thing (it is very irritating). I have had no time whatsoever to go after it, but I was under the impression that it was the result of the waste gate oppening and closeing. What do you think? I've been planning on persuing this line of thought by monitoring manifold pressure at waste gate hose connection.

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  • 2 months later...

Got it figured out. I replaced the engine on another matter and the car continued to surge after that. The headers were bad on one side so we replaced those (assuming the noise was setting off the knock sensor) and replaced the fuel pump and the hesitations are no more. Yayyyy, I say as they were realllllly annoying.

 

Simon

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