kamali

hi buddy,

i am from Iran ... i have a old oldsmobile cutlass ciera 1990 here ...

my car and engine running well when it 's in Park ... i have 900 RPM when it 's on Park.

but my problem is coming when i am driving and it ( Drive Gear )

1. when i turn the wheel steering to left or right(not so much) my RPM will come down to 1200 or 1500 even when i was pushing the gas pedal...

2. sometimes i am driving and my speed is around 40KM/H and engine RPM is around 1800 and i wanna get more speed ... i push the gas pedal again to get more RPM .... but engine wont get it ... and engine RPM will come down to 1200 RPM and in fact i can not get more RPM and speed ... i was pushing the gas pedal but nothing was happening ...

please help me no one working on GM cars here ...

sorry about my bad English ...
thanks a lot.
Ali,

Boldsmobile

Hi Ali, i will try to help but dont know if i can for sure.

I cant tell for sure if your problem is fuel, electrical or mechanical.

Will your engine go above 1200 RPM when in drive gear?

Does that car have a throttle position sensor (TPS). It is a potentiometer on the throttle body that signals to your cars computer how far open the blade is. If that model has one, you can test it with a DMM. Voltage or resistance should vary based on the amount the blade is open.

Another possibility is fuel pressure. Can you get a fuel pressure gauge to make sure you have proper fuel delivery? A bad fuel pump or clogged filter could be preventing you from getting the fuel you need under load.

Some other possibilities are a clogged air filter or clogged exhaust.

Those are a couple of ideas. I hope it helped.

kamali

sure , it have TPS ... it 's a 1990 cutlass ciera and fuel injection ...

i can test the TPS voltage when car is in parking ... and voltage is around 0.70 volt i think it 's normal for 900 RPM and in parking mode ...

i can not test the voltage of TPs when i am driving it ...

about fuel pressure ... there is some small valve beside the fuel injector and intake ... i have tested it and anything about fuel pressure was OK.

anything is working well when my car is in park mode .... but when i am driveing it by D or 1 or 2 that strange problem will come on ...

1. when i turn the wheel steering left or right ( for above of 35km/h)
2. when i got speed more than 60km/h in straight line ... and i wanna get more speed ... pushing the gas pedal but nothing happening and RPs will come down to 1200 RPM and maybe it wanna go off

70 cutlass s

I would have to start with asking has it had a tune up lately? Have replaced the fuel filter and put some fuel injection clean in the fuel tank?

kamali

i have replaced the fuel filter 3 months ago ... but didn't use the fuel injection cleaner before ...

but

what 's relation between turning left or right the wheel steering and low RPM when driving with fuel injection or bad fuel ....

engine working great when car is in park mode my engine is v6 3.1L 140 HP version ...

Boldsmobile

Try testing the TPS via resistance and you dont need to be driving to do this. I dont know the pinout on that TPS but as you open the throttle body you will get varying resistance. If you had the facotry service manual it would tell you the range but dont know if the value the manual provides are volts or ohms. I had a TPS go bad that only went created problems above approx 2500 rpm.

I am not sure how i can make a connection to the wheel turning.

Just to confirm:
Okay at idle. But if you turn wheel at idle does RPM change?
Bad when turning the wheel and between 35 and 60 km/hr?
Bad in straight line anytime above 60km/hr.?
Okay below 35 and turning wheel?

If it were only wheel turning that changed RPM, that might lead to some sort of issue with the power steering pump. I have never heard of a pump being a drain on the motor but i guess its possible. But you are also saying that above a certain speed you dont need to turn the wheel to have the issue?

Is your power steering pump making any strange noise? Put a long screwdriver on the pump and put the end of the screwdriver to your ear and use it like a stethiscope. Change RPM and see if you hear anything different.

When you did the fuel pressure test, did you also check the Fuel Pressure regulator? I dont know how that regulator is designed but if it has a vacuum line going to it, you need to check the pressure with it unplugged. At least my newer cars do it that way.

I am sorry i havent owned a 1990 Model so i dont know the specific components it has so i am trying to relate it to some of the things i have debugged on my cars recently.

kamali

it have a small change on engine RPM when i am turning left or right the wheel steering ... i think it 's normal as always ...

i have checked the fuel pressure in idle mode and it 's OK really
i have asked about the voltage on TPS too ... it 's near to normal voltage

about power steering pump ... it 's working perfect really

Boldsmobile

If that FPR has a vacuum line, did you check it with or without the vacuum line connected?

You said you checked the voltage on the TPS at idle and you admitted you can not check it while driving. So how can you state voltage is normal?

You cant figure if your TPS is good just by checking it at idle. The voltage varies as a function of throttle blade angle. You can measure it without the car running by measuring resistance instead of voltage. You need to measure its resistance when the throttle blade is 0% all the way through to 100%. If you only checked at idle you can possibly know if voltage is normal. The voltage varies as a percent of the throttle blade opening.

You did not answer some question i asked about the steering. But, because you say its working perfectly i wont ask again.