Mechanics

ROUGH IDLE, HESITATION AND VIBRATION ON A

1991 Ford Ranger

1991 Ford Ranger 6 cyl Two Wheel Drive Automatic 151000 miles

i just had my fuel pump, fuel pressure regulator, plugs wires and fuel injection serviced. Now after all that my truck idles rough and hesitates on acceleration and then after reaching a cruising speed letting off the gas and accelerating again it vibrates. When I took it in to the shop it was just having trouble starting and had none of these issues. I suggested they might have bumped or damaged a vacuum line but they say they have checked all that. They said they are willing to run a full diagnostic to find the problem at no charge but im hoping u can offer some advice that might help.
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Jak182
March 2, 2009.



Ok you mentioned some parts your replace but have you checked the fuel filter and how about the spark plugs. If the spark plugs were replaced was it before or after the injection cleaning? Get back to me and we will go from there.

Racefan966
Mar 2, 2009.
[quote=" racefan966" ]Ok you mentioned some parts your replace but have you checked the fuel filter and how about the spark plugs. If the spark plugs were replaced was it before or after the injection cleaning? Get back to me and we will go from there.[/Quote The fuel injection service and the changing of the sparkplugs were done after the the issue was discoveredwhen I got it back after the fuel pump and pressure regulator were replaced. Since they werent sure what was causing it and said that changing the plugs and doing a fuel injection service might solve the problem but since they werent sure they did the fuel injection service for free and gave me a discount on the plugs. The fuel filter was changed when the fuel pump and pressure regulator was changed.

Tiny
Jak182
Mar 3, 2009.
Ok if the injection service was done after the new plugs then I would pull the plugs and check them as the chemicals used for injection cleaning can glaze a plug and it will not fire right. I would also check the cap and rotor and ohm out the wires they should be no more then 7000 ohms per foot any more is no good. Also make sure the plugs are all gaped at.045. What plugs were used anyway? Get back to me and no need to quote me or you all I need is your response ok. Thanks.

Racefan966
Mar 3, 2009.
The plugs and fuel injection were both done after the fuel pump and fuel pressure regulator were installed. The problem occured before the plugs and fuel injection service were done so I dont think they are the problem. The only reason I had the plugs and fuel injection service done is because the service center mentioned that could be the problem and did the fuel injection service for free and only charged me for labor on the plugs. It had been awhile since either had been done so I had it done. They are gonna take it so another shop that has equipment that they dont have to see if they can diagnose the problem. They mentioned a possible problem with the ctatlytic converter. Does this sound like it could be the problem?

Tiny
Jak182
Mar 4, 2009.
Ok no I do not think it is a cat. I think you should test the TPS (throttle possition sensor). You do this with a digital multi meter. You leave the sensor pluged in and back probe the green wire with a paper clip and hook up your multi meter and turn the key on engine off. You should have about.8 volt with throttle closed now slowly and steadly lift the throttle it should steadly increase to 4.5 or 5 volts at wide open throttle. Now if while you are lifting the throttle the voltage drops or glitches then the TPS is bad and should be replaced. Let me know what you find here.

Racefan966
Mar 4, 2009.
So would that fix the rough idling, hesitation, and vibration? How much is something like that to replace?

Tiny
Jak182
Mar 4, 2009.
It will only fix the problems if it is bad. This is why I sent you the test procedure so you can test it and see if it is bad. I can not guarentee that a part will fix something when it hasn't been tested to see if it is bad. So I don't know if it will fix it without the test being done and told what is found. As for the cost it could be 20 to 40 dollars depending on which V6 engine you have.

Racefan966
Mar 5, 2009.
Well im taking it in Monday ill mention that to them. Thanx for your advice I appreciate your help. Ill let u know when its fixed wht the problem was so if someone else has this problem u can hlep them out as well.

Tiny
Jak182
Mar 6, 2009.
Ok do that. Get back to me with what they find as it may help somehow you never know. Besides I am allway's up to learning something new if it turns out that way.

Racefan966
Mar 6, 2009.
Just wanted to let u know what the problem was with my truck. They said it was a bad fuel injector. They said the truck was basically running on 5 cylinders. They replaced the fuel injector at no charge and now the truck runs great. One thing that doesnt make sense to me is that when they did the fuel injection service wouldnt a bad fuel injector been detected? Anyways just wanted to give u an update on what happened. Thanks again for your advice.

Tiny
Jak182
Mar 11, 2009.
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