Last chance for my SVX

[Guyver280z]

Ok, so far I cant tell what's the problem with my car, already took it to a lot of mechanics and they are clueless, they cant understand why the car runs rough on lower speed but it runs perfect in WOT... so this is the last try ill gieve to my car or Im going end up selling it... im tired of wandering around with no answers

So here are the simptoms:

1.- Sometimes it idles up to 2,000 rpms and it sloooowly goes down to 800 rpms

2.- Sometimes it idles at 500 rpms, but hitting the gas pedal fix it a little.

3.- If Im driving with the gas pedal from 0% to 50% the car feels rough, it jumps back and forth very violent, I hear misfiring on the exhaust (sounds like pof pof pof pof )But if I press 51% to 100% the car instantly works perfect and runs strong, no misfiring, no rough no nothing.... weird.

4.- No check engine light, it doesnt get hot.

Parts already replaced: Air Flow Sensor (Used but in better shape), Throttle Position Sensor (Used, checked voltage it works perfect).

Subject: 1992 SVX AWD with 5 speed tranny

Addittional info: Somehow my manual tranny is feeling like the clutch was slipping, but its not the clutch, you know.. when I press the gas all the way down the engine starts reving up but you cant feel a consistent acceleration.... then the engine revs down a little bit like it finaly catches up and then you start feeling a consistent acceleration.... Basically it feels like an automatic transmission that's about to break down... but its a manual, funny thing, 1st gear feels strong, 2nd 3rd and 4th feel like slipping. Can manual trannys slip like that?? I know its not the clutch because first I have a stage 2, second it doest slip while starting to move the car, even if I accelerate hard. And usually when I burn the clutch I get this hideous smell, but not when the tranny feel like slipping....

So please help me, Im desperate. I just dont want to go buy parts and parts that wont fix the problem... ans you all know... they are not cheap.

HELP ME PLEASE!!!!

[Guyver280z]

Nobody??

[The Hunter]

Email SVXFILES with your symptoms he's a expert on these cars. Maybe he can help.

[The Hunter]

My guess is a knock sensor but with no light HUMMM maybe your lights burnt out. Also I'd be checking those used parts out.

[Guyver280z]

Originally Posted by The Hunter

My guess is a knock sensor but with no light HUMMM maybe your lights burnt out. Also I'd be checking those used parts out.

Well, the light turns on when I open the switch, so I know the light bulb is working. And I checked the used parts... I mean, I checked the TPS with a multimeter and it worked great, also the original and it was fine. The MAF came from a newer SVX, it is pretty clean and the car shuts down if I disconect it, anyways, I find it hard that it could work exactly the same way as my old MAF.

I'll email SVXFILES, thanks for the advice

[Trevor]

Originally Posted by Guyver280z

Well, the light turns on when I open the switch, so I know the light bulb is working. And I checked the used parts... I mean, I checked the TPS with a multimeter and it worked great, also the original and it was fine. The MAF came from a newer SVX, it is pretty clean and the car shuts down if I disconect it, anyways, I find it hard that it could work exactly the same way as my old MAF.

I'll email SVXFILES, thanks for the advice

Don't panic as the idle issue should no be all that expensive. First things first.

Has all the flexible tubing associated with the inlet manifold been checked for leaks? Have the manifold bolts bean checked, as loose and leaking manifolds have been reported here?

Did you test the TPS and set it exactly in accordance with my instructions in the how too section?

Is the throttle control mechanism working smoothly and such that the throttles are closing exactly and completely, with the TPS moving in unison?

As you describe your other problem, it would appear to involve a slipping clutch. Why are you so sure this is not so?

The more detail you provide the better. Do not give up, difficult to sort maybe, but fixable.

[Myxalplyx]

Bad coolant temperature sensor? Does your car run rich when it is running poorly at low rpm? It's not getting hot so. Plus, the rough low rpm driving can be caused by excessive fuel going into your engine.

[ShiuludeSVX]

I'd be checking all the Vacuum lines also.
It sure sounds a lot like when I have encountered this type of thing in past cars.
Heck, with all the angles, and the fact that most of the lines originate thru hard plastic, oh yeah.

[Guyver280z]

Well, There's deffinetly a lot more to check now. Here is something I just noticed. If I let the enigne cool down lets say when I start in in the morning, while the engine is cold there is no failure... but after one or two minutes with the engine running as soon as the temperature raises the failure get worst and worst....

Same thing today after work the car was sitting all day and as soon as I started the engine it drove fine for a couple blocks and then slowly the failure started and getting worst the hotter the car got.

Also, I tried to set the TPS by all the ways I could, I even took a voltage lecture while installed and it seems to be in the right or at least close to the proper working position.

The throttle body opens and shuts smooth.

I dot think its a vacuum leak because I unlupgged some hoses while it was idling and it almost stalled on me, but as soon as I plugged them back the car went back to normal.

What about the IAC valve??? Can I remove it and clean it??? You think that could be it??

I have the service manuals (4 big books ) here is the troubleshooting table:

Poor acceleration/deacceleration:
1 ECU power supply
2 Air Flow Sensor
3 Fuel Pump
4 Pressure Regulator
5 Fuel Injector
6 Water Temperature Sensor
7 Throttle Sensor
8 Knock Sensor 1 & 2
9 By-pass air control solenoid valve
10 Crank angle sensor 1
11 Crank angle sensor 2
12 Cam angle sensor
13 Ignitor
14 Ignition Coil
15 Spark Plug
16 Induction Solenoid Valve

So from my point of view:
Cant be the ECU power supply.
Cant be the Air Flow Sensor because I replaced it with a used one and I find it highly unprobable that it makes the exact same failure,
Cant be the fuel pump because the car runs great while WOT and there's where it need more gas,
Cant be the pressure regulator for the same reason,
Cant be Fuel Injector... I dont think so, it will fail every time, idling and running,
Now Water temperature sensor.... is it the same that sends the temperature to the dashboard needle?? Because it seems to be woring fine, but as Myalpyx said, that can be a reason specially because it works fine while cold.
Throttle sensor... I know its working properly, anyways Ill double check with Trevor's guide
Knock Sensor.... it should give me a Check Engine light if something was wrong with the knock sensor right??? I hope its not a know sensor...sounds expensive
By Pass air control solenoid valve.... what the hell is that??? IAC Valve???
Crank angle sensors.... hope its not that
Neither the Cam angle sensor
Ignitor.... ok What is the ignitor?? the one that sends the signal to the coils??? Can it ibe?
Ignition coil... I dont think so, the car runs like a champ at WOT
Spark Plugs.... I deffinetly need to replace them eventually so i'll do it, Wich spark plug you reccomend?? Iridium?? Platinum??
Induction solenoid Valve?? what the hell is that?? Is it the weird flap thing inside the intake manifold?? Can it be the problem???


Somehow the manual relates a lot of problems with the water temperature sensor.... even knocking problems.

Ok, Im decided to work deeply on my car this weekend, but I want to be ready... so I need as much advice as you guys can give me. I love this car, honestly I feel like im never going to sell it and I want to be buried on it when I die So I need to bring it back to life.

I really aprecciate all of your help

[Hocrest]

Originally Posted by Myxalplyx

Bad coolant temperature sensor? Does your car run rich when it is running poorly at low rpm? It's not getting hot so. Plus, the rough low rpm driving can be caused by excessive fuel going into your engine.

Originally Posted by Guyver280z

Well, There's deffinetly a lot more to check now. Here is something I just noticed. If I let the enigne cool down lets say when I start in in the morning, while the engine is cold there is no failure... but after one or two minutes with the engine running as soon as the temperature raises the failure get worst and worst....

Same thing today after work the car was sitting all day and as soon as I started the engine it drove fine for a couple blocks and then slowly the failure started and getting worst the hotter the car got.

This problem is typical of the coolant temp sensor that Kevin mentioned.

[redsvx]

I just changed the water temperature sensor on my wife's Jeep Cherokee
It ran like a dog when it was hot and wouldn't start all the time
wouldn't idle properly ... I tried everything to do with fuel ... no luck

also the thermostat wasn't working at the right temp
changed that also and now it runs like a new car

I didn't know that temp sensor could control so much.

it's not the one that reads the temp for the gauge.

I'd try that first ...

[Guyver280z]

So, is this the sensor located in the Radiator??? or in the engine?? I mean if its not the sensor for the dashboard needle, so wich one???

Ill try to replace that.

[Hocrest]

Both coolant temp sensors are located right next to each other. At the rear of the engine on the drivers side. if you look under the intake manifold, you'll see two sensors threaded into the water pipe.

The one has one wire, it drives the gauge. The other has two wires, it drives the ECU.

[Guyver280z]

Originally Posted by Hocrest

Both coolant temp sensors are located right next to each other. At the rear of the engine on the drivers side. if you look under the intake manifold, you'll see two sensors threaded into the water pipe.

The one has one wire, it drives the gauge. The other has two wires, it drives the ECU.

THANKS!!! So this is the one I have to buy right??


The one with two connectors, I'll buy it today. I wish I wasnt driving my car today so it wouldnt be hot... I'll let you know what happened

[Hocrest]

That's it.

Make sure that the engine has cooled to the point of not being under pressure, or you'll get a coolant geyser.