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Alex
Alex, ASE Certified Technician
Category: Car
Satisfied Customers: 1141
Experience:  ASE Certified Technician
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2001 Rodeo: tp Sensors as per check engine code..throttle

Customer Question

Hello, I have a 2001 Rodeo, 3.2 V-6. Have just replaced both TP Sensors as per check engine code and also replaced the fuel pump because of preasure not exceding 38lbs. I have an intermittant miss when at idle throttle driving. When you give it hard throttle, it runs strong and doesn't seem to miss, but when you idle throttle at cruising speeds, it miss's and surges. I tried switching the coils around, it seems like it got worse. The plugs are NGK mid range and look to be new, very lite in burning color, no deposits. It idles smooth but you can power brake it in gear and it will miss.   I'm wondering if it's between the spark distribution in computer, Fuel injector miss fire or a coil problem.    How do I diagnose this problem? Thanks, XXXXX XXXXX
Submitted: 3 years ago.
Category: Car
Expert:  Alex replied 3 years ago.
Hello. My name is XXXXX XXXXX I'll be assisting you with your question.

Can you tell me which codes are currently coming up for the check engine light?
Customer: replied 3 years ago.
There is no check engine light on at this time, just the problem of the engine missing. The check engine light cleared after replacing the 2 TP sensors and disconnecting the battery to clear the computer. That's why I am wondering if it's injectors or coils.
Expert:  Alex replied 3 years ago.
Coil failures are very common on this engine. However I suspect the engine may not be misfiring. I think you may still have a TPS problem due to the surging at cruise and idle. These also have a common problem with the wiring harness to the TPS sensor. Look at the wiring and connector very closely and repair as needed. You can also wiggle the TPS wiring to see if you can cause the engine to run differently at idle while doing this.

If you're convinced it is a misfire, strongly suspect bad ignition coils.
Alex, ASE Certified Technician
Category: Car
Satisfied Customers: 1141
Experience: ASE Certified Technician
Alex and 10 other Car Specialists are ready to help you
Customer: replied 3 years ago.
Morning, This Rodeo has 125k on it and the main wiring harness is hard but looks undisturbed. Now, a fast question about the TP sensors. EGR valves are numbered for speicific aplications. I ordered the sensors from Rockauto at seperate times, first the less expensive one under the hood and then the one at the throttle pedal. They fit perfect but the Stamped numbers on the new sensors did not match the old sensors stamped numbers, is this system in need of matched units, is there calibration or talk between the two units that need to maintain the correct info. to the computer. Also, is there a way to test the coil packs? Before replacing the TP sensors, it had a problem with the "Reduced Power Light" and the cut in power with it, but since replacing the sensors, that problem has not happened again. The motor idles smooth with no fluxuation or surging, the miss developes under load in gear or as I said, at an inbetween throttle. If you get on it, there's no indication of it missing, it has great power and is smooth all the way up to high RPMs. What's the next step?
Expert:  Alex replied 3 years ago.
Thanks for the accept and reply. I'll get back to you with some answers on these questions this evening when I get home. Thanks again
Customer: replied 3 years ago.
Thanks for that. Another fast question for this evening. Could the "Reduced Power" system be shutting down for split seconds to be causing this, how does it work and is there a sensor/relay that could be faulty. I just drove it and pretty much figured out it's a feeling of the whole ignition is cutting, it's not just an individual cyl. miss, it feels like the whole system cutting off for fractions of a second. Thanks again.
Expert:  Alex replied 3 years ago.
Sorry for the delay. The reduced power message is just a warning indicator. It sounds like you solved that problem with the TPS. The pedal position sensor and throttle position sensors do need to communicate. The aftermarket sensors should not cause any problems, even if the numbers are different than on the old sensors.

At this point I strongly suspect a wiring issue and not a bad component. Even if the harness looks ok, the problem will most likely not be visible from the outside. I'd suggest wiggling the wiring harness (running at idle) ever so slightly as it goes from laying on the inner fender near the airbox towards the valve cover. Try moving it hard and soft in several different spots to try to get the best idea of where the problem is. Also look at the bottom of that harness as it sometimes rubs through to bare metal on the inner fender.

The most suspicious area for a wiring problem will be on the 3 small harnesses that go to the throttle body. I would open these up and inspect the wiring, and also try the wiggle test here.
Customer: replied 3 years ago.
Thanks, I'll try that. I just drove this Rodeo to the Coast here to check my boat, just did 360 miles with the missing problem. After a long stretch of running down 101, when I slowed and turned onto my turn-off, the check engine light and the reduced power light also came on again. I pulled over, shut it down for a few minutes, fired it back up to full power with no RPL on and full power. Check engine light stays on till I disconnect the battery for overnight. I can't work on much traveling here, but I will play with the wiring harness a bit. This is the 4th long trip I've taken with these problems and the car hasn't completly failed yet. I'll be a great little vehicle if the probs. get solved. Thanks for your patience and expertice. Ernie Ford.
Expert:  Alex replied 3 years ago.
I think that tells us that you definitely have a wiring problem, most likely in the 3 small harnesses that go to the throttle body/tps. Good luck!
Customer: replied 3 years ago.
Alex M, Thank you, You were Absolutly correct. I wiggled the wiring in front of the valve cover and it has smoothed out. I will leave Feedback and see if I can log back on and throw you some extra for your expertise. Thanks again, E. Ford.
Expert:  Alex replied 3 years ago.
Thanks for letting me know what happened. I'm glad you found the problem!
Customer: replied 3 years ago.
Thanks for that. I sent you a 5 buck tip, I hope it gets to you. Thanks again.
Expert:  Alex replied 3 years ago.
Thanks I really appreciate the tip. Come back anytime!

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