Ignition Timing Abnormalities (help!)
 

So I am working on a '93 Pick-Up 4WD MT w/ 22RE.

The initial complaint was a high idle speed. So I started checking the adjustments for the dashpot, throttle stop, and idle adjust screw. Someone adjusted the throttle plate so it would not close all the way and had the idle screw too far out. So I got the idle where I wanted it. Knowing these adjustments normally are done to compensate for something else, I checked timing (shorted connector etc.). It was way advanced, like around 30+ degrees with the connector shorted. So I adjusted down to 5 degrees and it idled better, but then it started back firing like retarded timing. So I looked further and noticed there was no audible or visual change in the way the engine runs when shorting the connector. My truck (a '92 w/ 22re) audibly changes to base timing when the connector is shorted. I know the connector goes to the ECU which then controls the igniter. I know the ECU receives the input because the Check Engine light flashes when shorted.

My theories are:
The ECU won't do the base timing function (bad ecu?)
The distributor gear is a tooth off, maybe throwing off the CPS inside?
The Igniter won't go to base mode.

Anybody have anything else?
Know where I can get a procedure to check the igniter? or ECU?

Next thing I am doing is pulling the distributor. Oh yeah and there aren't any engine codes.

thanks

Well it sounds to me that you took the TPS out of adjustment when you closed the throttle plate more then it was. This is the classic Adjust Your Throttle Position Sensor syndrome. DO A SEARCH!!!!!!!!!!!!!!!!!! :nono:

Thanks for the help.

You don't have to be a condescending jerk. Aren't people supposed to be helpful here? ISN'T THAT THE POINT?

:saw:

You remind me of the dickheads at the autoparts store.

Yep, classic TPS out of adjustment.

http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

thats more like it. i ended up finding that page last night. i have never had this problem on my truck. how can so many people get these out of spec? i even took off my throttle body to clean all the carbon out and my setting stayed the same.

I am still worried that the throttle plate was adjusted to compensate for some other problem.

Wish he wouldn't have taken it to the cracker jack techs.

Thanks for genuinely being helpful.

Sorry if I came off like that. I guess if you have never been here before. I just find that at least once every 2 days someone asks a question like this without searching. You usually get a much better answer when you search because someone has writen up a "how to" or step by step to do something.

If you have any questions on how to adjust it after doing a search let me know. Be glad to help :pat:

Check and adjust the TPS first. If you are haveing problems with the TPS (being bad or not adjusting correctly then you can set your timing at idle to 12* to 12.5* w/o the connector jumpered. That equals 5* with the jumper working.

I would check out the TPS, mark the #1 position (white out or bright marker) on the dist. base, then pull the dist. cap and rotate the crank by hand to 5* TDC compression #1 and see where the rotor is pointing. It should be right on top of where #1 is (the place you marked) when the base adjustment slot is centerd over the hole. If its pointing at #4 you are 180* out and need to rotate the crank 1 full turn back to 5*.
Hope that helps

When you do the procedure to get the TPS set, you'll see why they get out of adjustment so easily. The amount that the TPS needs to move to be in the correct position is so slight that even a slight hit can knock it out of position. Since it is right there by the thermostat, simply changing the thermo (something that seems to be necessary on the 22res a lot) can result in the TPS getting bumped out of adjustment.
Also, the factory screw setup can be a real PITA to get to in order to ensure that the TPS is held tightly in place so if it was ever adjusted, odds are the screws aren't tight. While you're at it, pull a screw for comparison, head over to True Value (I always find them to have the best selection) and replace the screws with allen headed socket head cap screws. Getting an allen wrench in there is cake making adjustment very much easier.
Don't overlook the possibility that the person before you had no clue what they were doing and got to dicking around with stuff without paying attention how to set it back to the proper setting. Skipped timing would be a possibility if the chain tensioners are about shot.
Good luck figuring out the problem.

Seems like the TPS issue is worthy of a sticky.

that exact problem drove me nuts, it was the TPS thing gone bad like they said.

new one and the time set right and it runs perfectly.

Believe it or not the dealer sold him a fuel pump for a no start. Next day it quit working again so he took it to an independant. They sold him a junkyard MAF (yellow paint writing). I can only assume they started adjusting things in order to find the problem. Makes sense though, the computer adjusts timing based on throttle position. I just don't understand why it wasn't engineered to go into diag mode regardless of TPS input. I guess 1993 was a while ago...

Fixed it.
 

Got the TPS back to spec. It doesn't really move that much and was tricky to set. If you ever do this just plan on removing the throttle body from the get-go. And buy some TB cleaner so you can get all the carbon off it while you have it out. Set the timing to about 7 degrees, reset the idle speed, and shes done.

I never knew there was an IG- terminal right by the diag port. Whenever I set idle speeds I try to use this tach I have for accuracy. Well my '92 has a nice old-school coil so its no problem connecting to the negative side. The '93 truck, however, had a new style coil without easily accesible terminals. So if you haven't seen this look inbetween the fuse block and diag port. Has as rubber cover that says IG-.

Actually, if you use a 90 degree offset screwdriver you can get to the screw on the bottom without too much hassle. I thought I had one, but couldn't find it so I just took an old little screwdriver and bent it over.
I wouldn't do it again without replacing the screws with the socket heads. In my case, it was definitely a problem with the last person to adjust the TPS not getting the bottom screw tight which eventually allowed it to rotate out of position.
Glad to hear you got it fixed.

Another great thread! When I have an issue like this come up, I instantly have a wealth of historic info to point me in the right direction! :great: