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I recently purchased a 2002 Rav4 and have been fixing it up. I decided to change the spark plugs and found oil in one of the spark plug hole. The valve cover gasket had failed and I replaced it along with the spark plugs. Ever since performing this repair my car has been surging forward. It happens occasionally when idling but usually happens under load. This problem did not exist before I did this repair.

My new spark plugs are iridium NGK plugs. At first I did not gap the plugs. When I noticed this problem I thought the spark plugs may need to be gaped so I did so. The problem continued. I have no check engine light.

Other information that might help solve the problem but I don't think so:

1) I thought the MAF sensor wiring could have developed a short because of movement during the valve cover gasket repair. I disconnected the MAF and drove the car around thinking that this would help diagnose. The car still surged in the same way.

2) I broke the rubber part of the spark plug boot when cleaning oil off of it. I initially thought it might be ok and drove around without part of the rubber boot. I have since purchased and installed a new boot thinking that this might be causing the problem. No luck.

I've run out of ideas and I'm hoping you guys might have some! Thanks in advance.
 

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Discussion Starter #3
stock ignition wires?
awdblazer, thanks for your response.

As far as I know everything I didn't mention in my first post is stock and as old as the car. I'm a bit new to working on cars but I am assuming that the ignition wires are the wires that plug into the spark plug boot (or ignition coil). If so, they are stock and I have thought about the possibility of a short in the wire. However, upon inspection I noticed that the wire that leaves the spark plug boot and goes to the ecu does not have any sort of plastic connector before it reaches the ecu. It seems I would have to cut the wire and sauder on a new one. Is this normal, am I missing something?
 

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It's possible that you damaged the ignition lead. It's possible that using it with the rubber boot missing caused arcing and damaged a coil.
I don't think iridium plugs are meant to be gapped either, as the centre electrode is so thin.
 

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Discussion Starter #5
It's possible that you damaged the ignition lead. It's possible that using it with the rubber boot missing caused arcing and damaged a coil.
I don't think iridium plugs are meant to be gapped either, as the centre electrode is so thin.
Thanks, do you have any suggestions on how I should start narrowing down what is causing the problem? Sounds like there are several potential causes.
 

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Easiest thing to try first is put the old plugs in.
I think yours has individual coils on the end of each plug connector, so maybe thats damaged?

Hopefully someone with more experience of your systen will come along.
 

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SlimJim16v is right. I dont think too that you dont have to touch the iridium, it is all set and ready to install. if you already gapped them, i recommend to replace them with new ones again. :-(

you may wanna check the injector circuit.
1. remove the air cleaner assembly first
2. check operation of each injector. have someone to help you crank or run the engine. if you have a sound scope
to check the normal operating noise or vibration. if you dont have a sound scope, you can feel each injector operating vibration with
your finger.

well, if no sound is heard, check the wiring connector, injector.

1. disconnect the injector connector. using an ohmeter, measure the resistance b/w the terminals resistance: 13.4-14.2 ohms at 20C or 68F
if the resistance is not in specs, replace the injector.

this a youtube link for your guidance.

https://youtu.be/ZVXchvHefNc

2. then reconnect the new one.
3. reconnect the air filter assembly.
4. drive the vehicle in about 30-45mins for the computer to relearn.

you may want to clean up your throttle body.
 

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When I hear about an engine surging my first thought is always to investigate the throttle body. It's an all-to-common problem for a lot of Fords and Hondas. Does it surge when idling? you can try unplugging the TPS and see if the idle improves.

-Saturday
 

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I'd start by checking for a vacuum leak. If the PCV hose isn't in place, this will cause it to run poorly, or surge. You said you removed the valve cover after all.
If that is ok, then I'd look at the rest of the hoses. (Vacuum not coolant). Also listen for a vacuum leak. You can also spray some carburetor cleaner around where you suspect a leak. If the idle smoothes out, then you found your leak.

Sent from my SM-N910V using Tapatalk
 

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Discussion Starter #10
When I hear about an engine surging my first thought is always to investigate the throttle body. It's an all-to-common problem for a lot of Fords and Hondas. Does it surge when idling? you can try unplugging the TPS and see if the idle improves.

-Saturday
I have driven about 300 miles with the issue (far more than I would like). I have only taken note of surging one time while idling. This happened at a stop light right after the car had been surging quite a lot on the road. Otherwise, the engine does not seem to have any problems at idle. The majority of surging occurs when accelerating or beginning to go up a hill.

ashtonybb and SlimJim16v, I believe you are right about the plugs, probably shouldn't have gaped them. I will start experimenting more when I have time and it's not Thanksgiving. Thank you for your suggestions.
 

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This sounds like an ignition misfire. Light loads tax the ignition system because the mixture is lean, and it takes a lot more energy to jump a gap with fewer fuel molecules. When you accelerate briskly, more fuel is added, and the spark easily jumps this gap full of fuel molecules.


Get a bottle of Windex or some type of soap/water mixture and saturate the spark plug wires and coils with the engine running. You should pick up the misfire easily this way.


Buy only DENSO parts. Anything else is not OEM.
 

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When I hear about an engine surging my first thought is always to investigate the throttle body. It's an all-to-common problem for a lot of Fords and Hondas. Does it surge when idling? you can try unplugging the TPS and see if the idle improves.

-Saturday
I have driven about 300 miles with the issue (far more than I would like). I have only taken note of surging one time while idling. This happened at a stop light right after the car had been surging quite a lot on the road. Otherwise, the engine does not seem to have any problems at idle. The majority of surging occurs when accelerating or beginning to go up a hill.

ashtonybb and SlimJim16v, I believe you are right about the plugs, probably shouldn't have gaped them. I will start experimenting more when I have time and it's not Thanksgiving. Thank you for your suggestions.
Hi did you ever resolve the issue?
 
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