1998 Tacoma Mystery Problems

My truck seems to have a problem with the throttle at 2300 RPMs or below. If I accelerate slowly it bogs and sometimes will "pop". If I stomp on the throttle it runs fine.

Background: I had a rebuilt 2.7 motor installed in my 98 Tacoma Excab. The original gave out at 538k miles. While there I replaced the clutch, water pump, alternator, TPS, fuel injectors, AC and I also had the upper control arms replaced. The one-man shop that did all this work also sent the ECM out to get it checked out. Long story short, the truck is not running right. The guy who did all the work seems puzzle with the problem given that we replaced almost everything. He said the throttle body could be the culprit. Its the original one from my old motor. I don't recall this happening just prior to my old motor going bad so I'm not going to replace the TB until I'm sure.

At this point I've lost confidence in this mechanic. If I knew how it was going to turn out after spending a pile of $$$ I would have never brought it to him. I guess my next step is to take it to the Toyota dealership to see if their diagnostic system can identify the issue. I did just get a check engine light but it came back as a faulty EGR valve which should not have any noticeable effects on the fuel/air management system. My guess is this is an ECM issue but I'm not an expert so I don't want to do anything until its gets a thorough diagnosis by someone who is. Any ideas or thoughts would be appreciated.

 

do not discount the EGR issue. If the EGR valve or its control system is malfunctioning that could be the cause of your complaint.

 

How many miles on the new motor since you replaced it? Have you made sure that your gas pedal doesn’t have wiggle to it and that the throttle cable is not loose and is snug/tight with the gas pedal?
Also have you considered asking any other shops about what they think? Any shops that specialize in Toyota’s that are honest and so fourth around you

 

If that egr is screwed up, there lies your problem...

 

Well I replaced the EGR vacuum module and I also tested the valve itself and found it to be fine. This was all after I drove it 3 hours to my new house and noticed coolant leaking from the back of the motor. I suspect the shop didn’t tighten down the EGR pipe connection. They also didn’t use any gasket or RTV during re-assembly.

Unfortunately the truck still runs the same “crappy” way. I’ve not made it to a Toyota dealership yet with this but that’s going to be my next move. It’s not displaying any idiot lights but I’m hoping they can attach it to a decent diagnostic machine and get some idea of what the issue is.

 

Spark plugs tight?

 

Good luck with this, please continue to keep us informed as to what is causing this....