No idea where to start (1 Viewer)

[TheMoose]

1fz motor
94 year

The truck idles rough when cold. Still close to 2k RPM but feels/sounds rough. It is very very rich on a cold start. Most of the time, it runs fine once warm. Intermittently, it will stutter, shake, and nearly die for just a moment. This only happens during acceleration from a stop and going up hill. The problem is showing itself more often as of late. Took it to a Toyota shop near my house and they couldn't find anything wrong as they couldn't replicate the issue. They speculated it to be a fuel pump but didn't want to throw parts at it for no reason. Has anyone has this issue? I don't know where to start looking. It stands to reason that something is moving ever so slightly away from contact but I don't know what or how. Any input is appreciated. TIA

 

[bajaphile]

Someone might chime in with a more eloquent reply, but I'd check for the following.

1) Make sure your check engine light (CEL) turns on when you start the truck. Sometimes the bulbs go out and you aren't able to see any codes. Verify there aren't codes stored, etc. I think 94 uses non OBDII, so you would jump TE1 and E1 in the diagnostics box and count the blinks.

2) Remove and check that your main intake tube does not have any cracks in it. They often fail along the ribbed sections, and you can't tell its broken until you really remove it and inspect. Seems like you might have a vacuum leak, so check your vacuum hoses as well.

3) Ensure spark plug wires are not damaged and are in good shape. Check distributor cap and rotor. Probably not your issue, but easy to check.

4) If you do think it is fuel related, look up changing your fuel filter "sock" that is in the tank. Those often cause problems after long drives however.

5) Check all grounds

 

[Dingotech]

1fz motor
94 year

The truck idles rough when cold. Still close to 2k RPM but feels/sounds rough.

It idles at 2K? That was happening to mine a couple of months ago, and it was a sticky throttle cable. A quick re-adjust solved the problem.

 

[shocktower]

MAP/MAF vacuum leaks

 

[TheMoose]

Someone might chime in with a more eloquent reply, but I'd check for the following.

1) Make sure your check engine light (CEL) turns on when you start the truck. Sometimes the bulbs go out and you aren't able to see any codes. Verify there aren't codes stored, etc. I think 94 uses non OBDII, so you would jump TE1 and E1 in the diagnostics box and count the blinks.

2) Remove and check that your main intake tube does not have any cracks in it. They often fail along the ribbed sections, and you can't tell its broken until you really remove it and inspect. Seems like you might have a vacuum leak, so check your vacuum hoses as well.

3) Ensure spark plug wires are not damaged and are in good shape. Check distributor cap and rotor. Probably not your issue, but easy to check.

4) If you do think it is fuel related, look up changing your fuel filter "sock" that is in the tank. Those often cause problems after long drives however.

5) Check all grounds

I checked the distributor and rotor the other day. They rotor had a slight bit of carbon build up on the contact portion. I cleaned it up. No check engine light but the bulb does work. Personally, I feel like it's an electrical issue just because it only happens when accelerating up hill. I will have to check the intake boot though and maf/map sensor. As for the grounds, anyone able to tell me where they are?

 

[TheMoose]

It idles at 2K? That was happening to mine a couple of months ago, and it was a sticky throttle cable. A quick re-adjust solved the problem.

It's just under 2k but only when cold started. It idles down to below 1k after warm.

 

[MountNGoat]

Did you ever gt this figured out? I'm having very similar issues.

 

[shocktower]

I checked the distributor and rotor the other day. They rotor had a slight bit of carbon build up on the contact portion. I cleaned it up. No check engine light but the bulb does work. Personally, I feel like it's an electrical issue just because it only happens when accelerating up hill. I will have to check the intake boot though and maf/map sensor. As for the grounds, anyone able to tell me where they are?

MAF is the thing you plug in on the intake, boot , has a wired plug they get dirty, and cause issues alos the boot it's self can have cracks, or a vacuum line is off or bad