: 94 STS Rough Idle, Jerking in overdrive with no load on moter!



MichSTS
03-19-04, 06:30 PM
My 94 4.6 still idles rough. When warm & ideling in park I try & feather the throttle to say 1000- 1200 rpms & it wants to go up & down between 1000 @ 1500. I can't find an even rpm level till I get the RPMS past 1500. Also I feel the throttle going down by itself in very small increments under my foot. I don't know if I had this particular symptom before the EGR cleaning. Hopefully I didn't leave a vaccume leak anywhere. Everything went together well & the gaskets were in good shape. The only current code is P036 (Right to left fuel banking difference). In gear it idles roughly at about 650 on the tack. The needle does move a little up & down but no more than 50 rpm's.

Going down the freeway in Overdrive say bet 55 & 75 without a load on the motor the car shudders & feels like the trans is slipping. Was about to take the trans back (had a rebuild about 5000 miles ago) & give the guy a hard time. Now I'm thinking the motor may be causing the problem since its happening in OD with very light throttle pressure. I give the motor a small load & it straightens out. If I step on the throttle at any RPM, the car runs like a bat out of h_ll. I do notice a large amount of smoke from the exhaust on the 1st romp. After that it will burn clean when I romp on the throttle. Its like its running rich & I'm cleaning out the carbon. The avg gas mileage is down around 3 MPG from normal all around (15.5) & around 5 mpg down on the highway. Highway normally 23 now 17 or 18.

So far I've cleaned my EGR valve & phenolic spacers & HAVE RAN A CAN OF BG44 through the engine with a tank of gas. The milage hasen't been checked since I did the cleaning but all the other problems exist still after the cleaning.

Appreciate any help. You guys have been great so far.

John from Mich.

BeelzeBob
03-20-04, 12:36 AM
My 94 4.6 still idles rough. When warm & ideling in park I try & feather the throttle to say 1000- 1200 rpms & it wants to go up & down between 1000 @ 1500. I can't find an even rpm level till I get the RPMS past 1500. Also I feel the throttle going down by itself in very small increments under my foot. I don't know if I had this particular symptom before the EGR cleaning. Hopefully I didn't leave a vaccume leak anywhere. Everything went together well & the gaskets were in good shape. The only current code is P036 (Right to left fuel banking difference). In gear it idles roughly at about 650 on the tack. The needle does move a little up & down but no more than 50 rpm's.

Going down the freeway in Overdrive say bet 55 & 75 without a load on the motor the car shudders & feels like the trans is slipping. Was about to take the trans back (had a rebuild about 5000 miles ago) & give the guy a hard time. Now I'm thinking the motor may be causing the problem since its happening in OD with very light throttle pressure. I give the motor a small load & it straightens out. If I step on the throttle at any RPM, the car runs like a bat out of h_ll. I do notice a large amount of smoke from the exhaust on the 1st romp. After that it will burn clean when I romp on the throttle. Its like its running rich & I'm cleaning out the carbon. The avg gas mileage is down around 3 MPG from normal all around (15.5) & around 5 mpg down on the highway. Highway normally 23 now 17 or 18.

So far I've cleaned my EGR valve & phenolic spacers & HAVE RAN A CAN OF BG44 through the engine with a tank of gas. The milage hasen't been checked since I did the cleaning but all the other problems exist still after the cleaning.

Appreciate any help. You guys have been great so far.

John from Mich.


Did you take the intake top cover back off and check the fuel pressure regulator for leaking fuel out the vacuum nipple on the FPR??

If the FPR is OK then I would lift up the fuel rail so that the tip of the injectors are visible and look for drips/leaks when the fuel pump is pressurized by turning on the key to energize the fuel pump.

MichSTS
03-20-04, 04:23 PM
Did you take the intake top cover back off and check the fuel pressure regulator for leaking fuel out the vacuum nipple on the FPR??

If the FPR is OK then I would lift up the fuel rail so that the tip of the injectors are visible and look for drips/leaks when the fuel pump is pressurized by turning on the key to energize the fuel pump.
Ok, back at you. I will take off the cover & check the FPR. If it leaks I'll replace it.
Injectors question. Are the tips of the injectors what plug into the blue plastic or silicone doughnuts? Can I turn the key myself, leave the fuel pump energised & run out & check them, or does it have to be done simontaniously w/another person? Is one drip a leak & if there is a leak do I clean or replace the injector?

Just trying to get my ducks in a row so I can finish the job.

Again Thanks in advance John

akaz87
03-20-04, 10:16 PM
Ok, back at you. I will take off the cover & check the FPR. If it leaks I'll replace it.
Injectors question. Are the tips of the injectors what plug into the blue plastic or silicone doughnuts? Can I turn the key myself, leave the fuel pump energised & run out & check them, or does it have to be done simontaniously w/another person? Is one drip a leak & if there is a leak do I clean or replace the injector?

Just trying to get my ducks in a row so I can finish the job.

Again Thanks in advance John
Hey just to let you know, you can turn the car on to right before start and it will pressurize to 50 lbs. You will want to look for a clean injector bottom. Yes a drip is a leak, there should be absolutly no dripping at all. You only need one person. If there is a leak try to clean it first with a little bit of cleaner, if that doesnt work just replace it. Its only 60 bucks and about 20 mintues. Not bad?

MichSTS
03-21-04, 02:36 PM
My 94 4.6 still idles rough. When warm & ideling in park I try & feather the throttle to say 1000- 1200 rpms & it wants to go up & down between 1000 @ 1500. I can't find an even rpm level till I get the RPMS past 1500. Also I feel the throttle going down by itself in very small increments under my foot. I don't know if I had this particular symptom before the EGR cleaning. Hopefully I didn't leave a vaccume leak anywhere. Everything went together well & the gaskets were in good shape. The only current code is P036 (Right to left fuel banking difference). In gear it idles roughly at about 650 on the tack. The needle does move a little up & down but no more than 50 rpm's.

Going down the freeway in Overdrive say bet 55 & 75 without a load on the motor the car shudders & feels like the trans is slipping. Was about to take the trans back (had a rebuild about 5000 miles ago) & give the guy a hard time. Now I'm thinking the motor may be causing the problem since its happening in OD with very light throttle pressure. I give the motor a small load & it straightens out. If I step on the throttle at any RPM, the car runs like a bat out of h_ll. I do notice a large amount of smoke from the exhaust on the 1st romp. After that it will burn clean when I romp on the throttle. Its like its running rich & I'm cleaning out the carbon. The avg gas mileage is down around 3 MPG from normal all around (15.5) & around 5 mpg down on the highway. Highway normally 23 now 17 or 18.

So far I've cleaned my EGR valve & phenolic spacers & HAVE RAN A CAN OF BG44 through the engine with a tank of gas. The milage hasen't been checked since I did the cleaning but all the other problems exist still after the cleaning.

Appreciate any help. You guys have been great so far.

John from Mich.

Its a joyous day!!
Yesterday I was driving around & noticed the check engine light was off while driving. This was my first lengthy drive since the repair. I immediately checked the codes & noticed my code P036 was history. Got home & in gear the car was ideling buttery smooth at 700 rpm's. I took off for a 60 MPH drive to see if I would get the shudder in overdrive without the load. No shudder whatsoever & the mileage is back. I'm excited to have been able to do this myself & only because of you guys. One thing I noticed is the engine seems more free & even coasting to a light, the engine slows the car down much less. How much would the dealer charge to fix the EGR valve & phenolic spacers?
Only issue I still have, & this is not affecting driveability in any way as of yet, is that I cannot in park, get the throttle to stay at 1000 RPM'S. It wants to flow up & down bet 1000 & 1500 with the peddle moving by itself down slightly beneath my foot. I am happy with things as they are but this is intriguinging me.

Thanks again!!:bouncy:

BeelzeBob
03-21-04, 11:01 PM
Its a joyous day!!
Yesterday I was driving around & noticed the check engine light was off while driving. This was my first lengthy drive since the repair. I immediately checked the codes & noticed my code P036 was history. Got home & in gear the car was ideling buttery smooth at 700 rpm's. I took off for a 60 MPH drive to see if I would get the shudder in overdrive without the load. No shudder whatsoever & the mileage is back. I'm excited to have been able to do this myself & only because of you guys. One thing I noticed is the engine seems more free & even coasting to a light, the engine slows the car down much less. How much would the dealer charge to fix the EGR valve & phenolic spacers?
Only issue I still have, & this is not affecting driveability in any way as of yet, is that I cannot in park, get the throttle to stay at 1000 RPM'S. It wants to flow up & down bet 1000 & 1500 with the peddle moving by itself down slightly beneath my foot. I am happy with things as they are but this is intriguinging me.

Thanks again!!:bouncy:

So did it just "heal" itself or did you find something else wrong....??

Chances are the idle speed control motor is going to need replacement as it may be getting lazy or the closed throttle switch is getting sticky inside the isc motor ...

MichSTS
03-22-04, 07:38 AM
So did it just "heal" itself or did you find something else wrong....??

Chances are the idle speed control motor is going to need replacement as it may be getting lazy or the closed throttle switch is getting sticky inside the isc motor ...
This is the first time in 6 months the chech engine light is off with no codes. I think the EGR repairs did the trick. The only thing different on the 2nd day test from the 1st was a fresh tank of fuel. The tank before had some BG44 in it. I'll be back if I have further problems. As for now I have some Walker Quiet flows I want to get on with cat back pipes as well.

Have a good one!!

John

joeveto
03-22-04, 04:26 PM
What is BG44?

MichSTS
03-22-04, 05:58 PM
What is BG44?
BG Products sells alot of good products. BG Products has a program that dealers use to clean your injection system. BG 44 is a product that the dealership puts in a full tank of fuel. They also run another product pressurised through the fuel rail & another in the intake. From what I understand it is the most effective additive you can add to your fuel to clean your injectors. It has worked wonders on many vehicles I know of, when nothing off the shelf would work. Make sure if you use if you mix it with a full tank of fuel. Follow the link below for more info & where to find it.

John


http://www.bgprod.com/bgconsumer/consumer.html