Hello! I recently purchased a 94 4 cyl toyota with the 22RE engine that was rebuilt due to a fire under the hood. It's in mint condition w/no rust. For months it ran excellant but now on occasion will lose power for a minute or so while underway and when at idle may also start to run rough with no warning and in some instances will return to normal in just a minute or so. We can't get it to act up when at the mechanics so no readouts. No check engine light ever. Just replaced fuel pump but no change. Opinions? Vehicles has 140K miles but was rebuilt about 15K miles ago.

rough idle multiple choice

rough idle (50%, 1 Votes)

22RE truck (50%, 1 Votes)

Total Votes: 2 Voting on this poll ends: 10/04/08 05:52 AM

Whaaa?

Do a tune up. Check ALL connectors under the hood. Check means unplug and replug, not just look at. Check EGR valve operation per the FSM. Need an FSM? Check the second thread at the top of the Index (85, 93, et. al. Toy FSM's ~Reviewed 01/01/2008~ ).

do basic tune up. i am thinkin it could be your TPS. throttle position sensor, but not exactly sure

tks richard! manual helpful. thought we would replace the engine coolant temp sensor for starts. hope one is easy to obtain thru toyota. then on to the EGR valve. btw it's a 94 (me bad) but assume that the 93 manual works. believe the 94s were the last year.
22RE

There is virtually no difference in the 22RE motors from one year to the next, except for cleanliness and VSV here and there. If you just have money to burn, fine, but would strongly suggest testing sensors before running down to buy them. You won't be real happy with what Toyota charges for most things. A junkyard and several online parts places are usually much cheaper. Check out JC Whitney and Summit Racing, and a couple of your local parts stores should be on speed dial <img src="/forums/images/graemlins/notooth.gif" alt="" />

I hear you Richard. The headache is that the problem (rough idle/loss of power) only happens once in a while. Seems like something is going (perhaps a hairline break in a printed circuit)but we have waited for a few months for it to go or at least a check engine light. Once a few weeks ago while my local mechanic had opened the hood to take a look, the engine did start to run rough for a few minutes but came right out of it prior to getting any testing equipment hooked up. As you can imagine, it's a real concern to be towing a trailer full of lobster traps up a hill and having the engine run out of steam!

we're at a loss as how to proceed and our mechanic friend feels the same was as you do about throwing parts at it. We don't have the skills and I don't think he will be willing to use preowned components. The truck is too much of a sweetheart to walk away from. The first sensor only costs arount $71 bucks.

George <img src="/forums/images/graemlins/barf.gif" alt="" /> <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

Im usually the one asking for help around here, time to give back alittle..

Maybe a vacuum leak..? in the EGR system?

I found some cool info a while back to find vacuum leaks. Instead of using carb cleaner/starting fluid to find a leak, an unlit propane torch...since its a gas it can get into the more nuisance of cracks and such.

A vacuum leak is certainly a culprit, though if it is intermittent, that seems to be not too likely. Once the engine hits operating temp, a vacuum leak is going to usually cause a consistent rough idle. I won't go along with the unlit propane around an engine that produces spark while running. Even though a build up of gas is unlikely, the consequences seem a bit drastic.
I would follow the FSM step by step in the troubleshooting section for a rough idle. I have done the same thing and it is time consuming, but also provides some thorough peace of mind about the ECU components. If you are not confortable with a multimeter, read the directions on them. They are easy to use and only take a little practice. Start with easy to get at stuff like the AFM and test it out. I think I mentioned earlier about the connectors and how important it is to unplug and replug them, not just look them over and call it good. This goes for the Ox sensor as well. Being under the truck, some people aren't willing to make the crawl or get dirty, but it has a connector like all the other sensors. Check the Ox wiring as well. It can droop and burn and cause faulty readings without tripping the Check Engine. And check your check engine codes, whether the light is on or not. Codes are stored, even intermittent ones. How long has it been since an emissions test? Any irregularities? How many miles on the catalytic converter? They do stop up, but very gradually. Well, just some thoughts.

When you lose power on the highway, is there no power at all, i.e., it drops to idle and no matter how much gas you give it it doesn't respond? If this is the case it is likely a speed sensor.

Sensor issues usually take a long time to register a code, since they only fail every X amount of cycles. I had a speed sensor do this, in the beginning it was about every 600 miles. and of course wouldn't produce the problem the 3 times I took it to the dealer. It took about 7 months before it finally threw a code.

I think you have more than one sensor issue, the same sensor shouldn't cause a problem at idle and at highway speed. The TPS really shouldn't be the cause of both problems.

Since you don't plan on ditching the truck, and don't feel safe using it for for what you need, or want to risk driving it for months until the problem manifests itself with a code, you really don't have much of a choice but to start replacing sensors. I would start with the cheapest ones that could be the issue, that is after a tune-up(new cap/rotor, plugs, plug wires, valve adjustment, cleaning the PCV and EGR valves etc.). You may also want to pull the injectors and have them rebuilt/cleaned/tested, you could have a problem w/fuel delivery under a heavy load.