bgilbe

I have a 93 pickup with a 3vze engine. I rebuilt the motor and everything seems to be fine except for the timing. when I put a jumper on te1 e1 the idle will not drop and the timing doesn't change so I can't set the base timing. I can't adjust the idle either. Turn the idle screw and nothing happens. I was getting a TPS error code from the computer so I replaced the TPS and readjusted it. Still got the error so I replaced the computer. No more error but I still can't adjust the idle. Does anyone have any idea what could be causeing this?

gwhayduke

I didn't get a RPM drop when I jumpered the OBD, but was able to time it anyway. The jumper is to keep the ECU from advancing the spark and making it difficult to set the base timing. You be able to just set the idle, jumper it and time it without second guessing the ECU.

AgRunner06

Are you sure you adjusted the TPS correctly?

radrex

I'm voting for TPS adjustment.. Almost for sure.

Maddog

If it helps at all,when i unjump my engine after setting base timing it moves(advances) to about 15 degrees btdc ,after setting at 10 btdc jumped,so if you still cant get the jumpering to work try setting at 15 ,& see how it goes.
but thats not the only problem you have buy the sounds of it.

Babypig

I'm gonna go out on a limb and say that the signal generator in the distributor is behind this. I have the same kind of trouble. Timing bounces all over the place. Immpossible to nail it down. The signal generator in my truck has tested bad. Couldn't simply find that part though without buying a whole new distributor. 400 bucks later, no more timing problems. Might be your problem may not, but it's somewhere to look.

Good luck
Steve

P.S.
let us know what it turns out to be to keep the archive up to date for future similar problems

bgilbe

I'm convinced it's not the TPS setting. Between the old one and the new one I just installed I've adjusted it about 7 times. Both on the truck and off, one had behind my back, standing on my head and blindfolded. I'm pretty good with a multimeter that way so I'm sure it's on. I did take Maddogs advice and set the timing to about 15 degrees. Seems to clean it up quite a bit but I still think something else is wrong. I can get the idle set to 800 but there seems to be a bit of a 'rumble' for lack of a better word at idle. The rpms don't bounce around and the engine doesn't seem to 'lope' just kinda shakes the truck a little. I'll try to look into the Distributor thing and see what I can come up with. How did you determine that the signal generator was bad? Anyway, thanks for all the tips and I'll let you know if I find anything else out.

dusty98

Just a long shot here, but I'd verify that all the vacuum lines are routed correctly and connected. Let us know what you find out.

nightsurfride

Something in the air tells me vac. leak...

bgilbe

Actually I did have a bad route on one of my vacuum hoses. The engine didn't really want to run at all then. I documented the rebuild pretty well with digital pictures so I'm sure the lines are run correct now.

What's that old trick for vacuum leaks. Is it spray ether around the intake and see if anything changes? That one has always made me nervous.

nightsurfride

I do it at work all the time. Just take some brake clean and spray around intake or any other air intrusive areas and if the RPMs change, you got a vac. leak. Obviosly don't sit in one area for a while spraying or spray on the hot exhaust for fire reasons, but all else is fair play.

bgilbe

OK, I'll try it with brake clean tomorrow and let ya'll know what happens. I just remember having some close calls being a little to generous with the ether on my old FJ40. Don't like regrowing eyebrows :pat:

bgilbe

Well, doesn't seem to be any vac leaks. I suppose I'll just have to live with the idle rumble. I'm happy with the timing now but still not sure why it won't drop to base timing with te1-e1 jumped. Thanks for all the help.

ChickenLover

I had the same problem. After adjusting and readjusting the tps I stil couldn't set the base timing correctly. After taking my intake apart last week and cleaning it, I decided to give the tps adjustment one last try. I found the instructions for setting the tps I got from this forum to be very confusing and I couldn't seem to get any of the measurements on the multimeter to match up to the instructions.

I hooked the meter up to the bottom plug and the 3rd one up from the bottom on the tps. I stuck a feeler guage in the throttle stop (.762 mm). I started with the tps rotated all the way clockwise, I slowly rotated it CCW until the needle on the meter came alive (spiked). I tightened it down at exaclty that point. The feeler guage was only used to give a little insurance.

My prior attempts at adjustment (following the instructions I had) had left the tps in a position not similiar to the stock one I had replaced. The adjustment mentioned above left it right where I remembered the stock one being. After putting my intake back together I was thrilled to see my base timing right back where it should have been ( a couple degrees off because I had been setting it by ear before).

Now with the terminals jumpered the timing would retard about 2* (like it should, but wasn't doing before). The runner's runnin' right again. You should know that the method I mentioned above is not a proven one (to the best of my knowledge). I might have just been lucky. So proceed at your own risk.