Hello. I am new to this forum and am looking for any advice. I have a 94 pickup with a serious running problem. It started last night while the wife was driving. The truck will start hard and idle kind of rough. Under normal load it will make a pinging noise (sounds like detonation, or possibly a light engine knock?). It actually sounds like a small diesel motor for some odd reason. It will stop that noise at about 3,500 rpm but it is low on power and sounds like the intake tube is off or something. A friend said he was 90% sure it was the MAF sensor on top of the air filter box, or possibly the el-cheapo wires I used during the last tune up. I did drain all of the oil and checked for metal flakes, everything seems fine there, and no loss of coolant so I don't think it is a head gasket.

Any thoughts on what this might be?

 

Could it be your timing? When was the chain replaced last? Just before I changed mine a couple of friends commented that it sounded like a diesel.

 

Not sure when/if the chain was replaced, but this was a "sudden" change in running conditions. Would the chain cause the engine act like that so quickly? I wasn't too sure that a chain could physically skip a tooth, or become that loose. Of course I have never looked at one, so I it is only an assumption.

 

changed the spark plugs any time soon and what name brand
cuz when i changed mine i thought that the moast expensive was the best but did kinda the same thing. so i had to go to stock plugs.

 

I used NGK-R's about a year and a half ago. I took them out last night and they all look the same, but had a strange smell to them at first. The exhaust smelled similarly strange.

I'll be getting new plugs and wires tonight to try.

 

i'd take a look at the timing chain. if you pull the valve cover you can get a look down at it. check for rubbing on the timing cover, and see that it doesent look like its falling apart, and that the guides aren't broken.

a full tuneup would be my recomendation if the timing chain is in good shape, check the tps, and do the timing. replace the plugs with ngk, or denso, and check the resistance on the wires and make sure theyre in spec.

edit: while I was you posted that you already have ngks

 

I think I'll try the basic tune up stuff first, and then take off the valve cover. It looks like a pain in the butt with all of the vacuum hoses, etc. but I know that if the tune up doesn't do it, it may be a lot more serious.

No one thinks it may be the MAF sensor as a friend pointed out? I would hate to buy one if it is not needed. Does anyone know if a MAF out of a '92 4runner with V6 would have the same MAF sensor? I doubt it, but a friend of mine has one of those so it would be easy enough to try.

 

All of a sudden like that might be head gasket. I had that happen to my 88. The gasket between 2 cylinders blew out. This caused a bad ping and no power.

 

the valve cover is easy to remove. all the vacuum hoses go to a plate that is held on by 3 12mm bolts. remove the bolts, and you can flip the plate out of the way and get the valve cover off with 4 more 12mm bolts

 

It's not actually a MAF sensor. (mass airflow sensor) It's an air meter that uses a flap to determine the amount of air entering the engine. A MAF uses a heated wire that is cooled as the air flows over it to meter fuel. These get gummed up sometimes and can lead to problems.. I don't see the air meter getting messed up as much though. It seems simpler... Not saying it's not the problem, but I don't hear of them having problems as often as MAF sensors. Might want to check vacuum lines, plugs, and wires for rough idle situations. Like dude said it could be a head gasket too.. With the engine cool, take the radiator cap off, start it and look for bubbles.. Also see if there is funky smell or steam coming from the exhaust.

 

one other thought is if the cheap wires were bad or you had a crack in the distributor cap. To check you can run it at night with the hood open, and look for arcing

 

Thanks for the suggestions. I'll check the easy stuff tonight and let you know the results.

 

Well, tried the wires and plugs last night and nothing changed. It appears that it is the timing chain tensioner. One side of the chain is tight, and the other side is really loose. There are actually grooves ground in on the inside of the timing cover where the chain was grinding when it broke. It must have been throwing the electrical and valve timing off which is causing the loss of power and detonation.

Thanks for the tips on this issue!

 

Sorry to bump an old thread but I just read this and wanted to correct it. There is more than one style of MAF sensor. The 22RE uses a flapper style. The other kind that you described is known as a hot-wire. I just didn't want anyone else to read this and believe that incorrect information.

 

Is it the tensioner or the guide that broke? What typically happens with these is that the plastic guide on the drivers side breaks. Then the plastic pieces fall down into the timing cover and get in between the lower timing gear and the chain, causing the chain to either break or jump time. Then they finally make there way into the oil pan when the pieces get ground up enough. Don't run it any more either. If your lucky, it did not cause the valves to contact the pistons. The worse it gets, the more likely it will be for that to happen. Then you have a lot more to fix.

 

Hey guys I found this thread and wanted some input as to what to look for when popping the valve cover I also have a 94 pickup 22re and when i start it up it starts really rough sometimes and only idles at about 450 RPM's but it has never stalled out yet and I also have a loud rattling/ticking when its idling the truck seems to run fine but should I be concerned that it may be the timing chain guide's I find it hard to believe that it would be that the truck only has 50,000 miles on it

 

pull the cover, and look down into the timing chain cover, with a flashlight, and see how the guides, and chain look. check for wear marks in the valve cover.

might as well check the valve clearances while you're in there. low idle is probably caused by other things, but if you think the chain is going might as well check that.

 

My 94 had the same rough idle upon startup. It also was revving sometimes when warm. I had to adjust the idle and replace the spark plugs. That seemed to do it.

 

I just changed the spark plugs about 3 weeks ago it did help with excelleration but I still have the startup problem how do you go about adjusting the idle on the 22re

 

gavy, there is a idle air bypass screw on the top of the throttle body. A flathead screwdriver and left or out is higher rpm and right is lower.Perform when completely warmed up before you start make sure the coolant is full. Low coolant levels will mess up the adjustment