ENGINE LOSES POWER INTERMITTENTLY.

  • Tiny
  • Aykoss
  • 1994 Toyota 4Runner
  • 31,147 miles

Hi, I have a 1994 toyota 4runner v6 sr5. I have a problem with the engine losing power intermittently. The motor loses power and and if I put the clutch in and rev it runs perfect again. It started doing it only on one particular slight hill on my way to work. (Steeper hills were fine). Then it gradually got more frequent. Changed fuel filter. Still did it. Changed spark plugs, and it ran perfect for 1000km or so, then it started again but way more frequent. It doesn't seem to do it too much above 3000rpm. I have taken it to three different mechanics they had no idea. "Drives beautifully" they say. Any help would be greatly appreciated. Cheers!

Sunday, July 1st, 2012 AT 4:31 AM

19 Answers

  • Tiny
  • mhpautos
  • Expert
  • 29,860 posts

Can you tell if it feels like a miss fire (electrical ) or a gradual power loss more like fuel starvation, have you check the fuel pressure as yet?

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Sunday, July 1st, 2012 AT 5:12 AM
  • Tiny
  • Aykoss
  • Member

Gradual power loss until I pump gas, then runs perfect again. Sometimes when idling rpm will drop from 1000 to just above zero eventually stalling after around a minute. Haven't checked the fuel pressure, will read up on how to. Thanks!

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Sunday, July 1st, 2012 AT 5:58 AM
  • Tiny
  • mhpautos
  • Expert
  • 29,860 posts

Let me know what you find with the fuel pressure.

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Sunday, July 1st, 2012 AT 7:17 AM
  • Tiny
  • Aykoss
  • Member

Will do. Wanted to ask, is there any reason it ran perfectly for a while after the spark plug change? Coincidence? Also could it be the o2 sensor? As I was running it on e10 fuel for a while and apparently that can make them fail.

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Monday, July 2nd, 2012 AT 12:12 AM
  • Tiny
  • mhpautos
  • Expert
  • 29,860 posts

If the O2 sensor fails you will normally get a code up for over rich on one or both banks, manually testing o2 sensors are not very easy, they do wear out and as they do they tend to cause a rich mixture, an exhaust gas analysis will b e the best way to test for this.

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Monday, July 2nd, 2012 AT 12:36 AM
  • Tiny
  • Aykoss
  • Member

I can't afford to have it in the mechanics at the moment. Do you think it's worth me cleaning the maf sensor? I have no check engine light showing though. Thanks.

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Friday, July 6th, 2012 AT 7:53 AM
  • Tiny
  • mhpautos
  • Expert
  • 29,860 posts

Can't hurt, give it a go and see if it helps any.

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Friday, July 6th, 2012 AT 8:51 AM
  • Tiny
  • Aykoss
  • Member

Hi, having trouble locating the maf. Took the air box off and assumed the maf is the thing bolted to the top, it has a little door flap thing inside and behind that a little plastic tube sticking down. Is that the thing I have to spray? Cant find any info or pics on the net, do you have a diagram of it? It's not even in the manual. Thanks again for you help!

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Saturday, July 7th, 2012 AT 4:21 AM
  • Tiny
  • Aykoss
  • Member

Ps. The air filter was absolutely filthy dead flys and small rocks and sticks in it!

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Saturday, July 7th, 2012 AT 4:23 AM
  • Tiny
  • Aykoss
  • Member

So I cleaned the rocks and dead fly's out of the air filter (will buy a new one tomo) and the truck runs a hell of alot better. Still cant find the MAF (the thing I was looking at I think is the AFM) would still like some info on MAF if possible so I can clean it when I change the filter. Thanks.

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Saturday, July 7th, 2012 AT 6:14 AM

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