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<Insert witty title here>
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Discussion Starter #1 (Edited)
Howdy guys,
My 99 4Runner SR5 2WD v6 has just at 150k miles on it and she is starting to show her age. In the mornings she just doesn't want to get out of bed. What happens exactly is for the first 3-4 minutes she just doesn't want to accelerate. She starts fine, I've tried to let her sit in the driveway and idle until up to operating temp and that doesn't help any more than trying to get right out and drive her cold. What happens is I back her out of the driveway just fine, then when I put her in drive and give her gas she sputters for a second and has a lack of power. Then after a second she gets up and goes and runs just fine. There is no hesitation or lack of power once she is up from idle. It will do that for the first 5-6 starts from a full stop and then won't give me any more issues until she completely cools down again.

Her resume: Last year was getting a MAF code so I replaced it. I had gotten a TPS code for about a year before but cleaning it (or removing and putting back on) removed the code and had got me through to the same point I got the MAF code, so I replaced the TPS at the same time. I took the throttle body off and sprayed it out really well, but I didn't replace it at the same time I replaced the TPS. I had no issues with the car until about a month ago when all this hesitation until warm stuff started up. I haven't changed the plugs in a couple of years, but the car doesn't get many miles on it anymore since it is only driven more than 5 or so miles 2 times a week. I have a new set of OE plugs (NGK I think, still in a bag from a vendor when I bought them a couple of months ago) as well as a set of valve cover gaskets because I have some oil leaking from one. I put a new filter on about a month ago when the hesitation first started, didn't help. I ran some type of gas cleaner through, a lucas product maybe (clear skinny bottle), and didn't help. I've tried running the highest octane through in case it was a detonation issue, didn't help.

So i'm thinking I'll pull the MAF again and give it a spray, guess it could go out since I have no idea if it was a Denso or not...seems like it was though. I'm not holding out hope it is as easy as new plugs, there is no other hesitation and I've never had a plug start working "when it warmed up". I did read at one time that there is an adjustment you can make to the TPS, but I didn't see any way when I installed it. I don't even remember the eye-holes being oblong to be able to "twist" it slightly.

The not throwing a code is the strangest part. I haven't pulled any vacuum hoses or done any checks like that, and I don't know the thoughts on seafoaming but have a buddy recommending that. I did a search here and on Google and couldn't find any one with my issue, everyone else seems to have issues after warming up.

Thanks in advance.
 

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If it only does it when it's cold and goes away when it warms up, I think of things that are only in play when it's cold.
The first thing that comes to mind is the cold start injector circuit.
Maybe it's not operating correctly.
 

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<Insert witty title here>
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Discussion Starter #3
If it only does it when it's cold and goes away when it warms up, I think of things that are only in play when it's cold.
The first thing that comes to mind is the cold start injector circuit.
Maybe it's not operating correctly.
Thanks, I'll search here and google for info on it. Since it needs it anyways, I'll start with the simple (plugs and wires) and progress to the more difficult stuff.

I'm just stumped because I can't find many people with an issue like this. She runs perfect in idle and once I get going. If this were my gokart I'd just bump the idle up a bit and be done :rofl2:
 

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Discussion Starter #4
Temps got about freezing here today so I got out and worked on it. Pulled codes, even with no CEL and got a P0120. I replaced the TPS within the last year, or around a year, so that shouldn't be the issue but you never know. I have heard a dirty TB can make the TPS go haywire, so I pulled it off and cleaned it really well with TB cleaner and a nylon brush. I also took the MAF out and sprayed it with MAF cleaner. While I had all that stuff off I changed the spark plugs. Wires all looked good, the plugs did not. They were Bosch, not dual electrode NGK's like I put back in. With everything buttoned back up I took her around the block and the initial reaction was that the hesitation on first acceleration is gone.

Now I have an issue of idle being too high. After it warmed up it was still idling at 1200 RPM in neutral. Started at 1700 then came down when it warmed up. With it in gear I was able to just take my foot off the gas and it went up to 15 MPH and shifted to 2nd gear in a pretty short amount of time.

So I guess I'll get back in and make sure that there aren't any linkage binding (peddle is smooth so probably not) and otherwise that TPS may be out. Will need to hook up the meter to check the readings but didn't have time today with my 2 year old helper running around with my tools every time I set one down :)
 

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Discussion Starter #5
Another update after a few days of driving. Before I did anything, there was no CEL on. I pulled a P0120 code the morning I started to work on it (prior to touching it, checked for good measure) but the CEL wasn't on. After pulling the TB and cleaning it and replacing plugs, I now have a CEL on and the P0120 code is back. I reset it after I did the work, i did not pull the neg terminal to reset the computer though. The hesitation when first trying to accelerate is still there, doesn't seem to have gotten any better. The idle now sits really high, even when warmed up.

The odd thing, I noticed that after the 4runner is warmed up if I turn it off and turn it back on again, the idle will be normal. reminder of my issue, even when warm the car will sit at about 1100 RPM in drive and at idle. If I turn off the car, start it right back up, put it in gear it will idle at around 700 which has always been normal for this one.

I'm going to put a meter on the TPS harness and the sensor itself to see if I just got a lemon. The only other thing I could think is to check for air leaks since I did notice a few smaller vacuum hoses that showed some signs of stretch.
 

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You do need to disconnect the negative battery cable. This will reset the ECM's learned value for closed throttle position. If the ECM thinks the throttle is open it will not operate the idle air control valve.
 

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Discussion Starter #7
You do need to disconnect the negative battery cable. This will reset the ECM's learned value for closed throttle position. If the ECM thinks the throttle is open it will not operate the idle air control valve.
I'll do that today! I have been thinking it might be an IAC issue and was planning to pull the TB back off and open that up to clean it (didn't have new gaskets so left it closed and was careful when cleaning TB last weekend). I'll try the battery disconnect reset first.

:thanks:
 

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Discussion Starter #8
Guess I didn't come back and report the findings. Resetting the ECM didn't help. Went down to the parts house and got an OE TPS, popped it on, reset the codes with the batt cable off, and she runs like a champ now.

While I was under there listening to her idle I noticed some smoke on the passenger side. I've had a burning oil smell for a bit but never seen any drips. I figured it was the valve cover gaskets but haven't replaced them even though I have the parts. I actually saw the oil puddled on the exhaust collector, where it was sitting and smoking. I grabbed a socket and checked to see if the valve covers were loose, and every single bolt was way less than "finger tight". So I snugged them all up a bit, on both sides and took it up to the car wash. I blasted off all the oil on the collector and cleaned up the covers a bit...no more burning oil smell. So everyone else might want to just check those valve cover bolts, these were so loose I'm not sure how they hadn't rattled up and out of the car.
 
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