I just replaced the 22R engine in my 94 4x4. I got to the end of the job and, despite having to re-install the distributor a couple of times, managed to set the timing to 5 degrees BTDC with a nice smooth idle. I then set about re-installing the hood and some other stuff, then came back to do a leak check and road test.



When I re-started it, it would barely start and not run without some throttle. I checked the timing and it seemed advanced and very unstable. The distributor had not moved. I loosened the distributor to reset the timing but I could not get it close to 5 degrees without stalling. The timing was also was very unstable.



I fear a timing chain jump, but I think this is unlikely since I replaced all timing components and didn't hear any noises when I restarted the engine.



Any help would be appreciated.

 

After you had started it, did you adjust the timing when the engine was at operating temp? or when it was cold?

 

When I set it to 5 DBTDC, it was cold. I have tried to reset the timing with the engine hot, but it is really jumpy and when get close to 8 or 5 degrees, it virtually stalls.

 

did you short the t1 (or te1) and e1 terminals in the diagnostic connector before adjusting the timing?

 

Darn, I did not. I refered to the shop manual for most of the engine replacement but didn't check the manual for the timing instructions. I only checked the tune-up spec for the 5 DBTDC value.

I feel a little foolish, I must say.

I will try to short the connector and reset the timing and see how it goes.

Thanks for the quick feedback.

 

seems like everyone's made that mistake at least once.

 

I shorted the connector and warmed it up. It still runs really rough at low idle and I can't get anywhere near 5 DBTDC. In fact, it doesn't run that great at 12-ish DBTDC.

Again, it ran like a kitten and was rock solid at 5 DBTDC when I first set the timing - until I shut it off.

 

what is the idle speed now? should be ~750 in neutral. the idle speed has to be correct when the timing is set so you might have to adjust both until you get both correct.

 

Mybe the idle is too low. It certainly sounds that way.

I don't have a tach, however. If I can't rig one, I'll guess I'll have to buy/borrow one.

I must say, I am still confused that the truck seemed to be ok then changed. Just for curiosity's sake, I'll try again w/o a tach tomorrow morning with the engine cold to see if I can reproduce the good performance.

 

just a heads up-
when you short the connector the engine speed should drop. if it doesn't the throttle position sensor is probably either bad or needs adjusted. the tps must be adjusted properly in order to get the timing and idle speed set properly. I'm not saying it isn't adjusted, like I said 'just a heads up'.

 

do you mind if I ask why the engine was replaced and/or what work was done?

 

My original engine had 184k and I had never changed the timing chain. Neeldess to say, the chain was worn and it skipped two teeth. I found a worn TC cover as well. I had also noticed a fair amount of oil consumption, so I figured it needed at lead head work (valve seals) and probably rings. Instead of overhauling my engine, I bought a used one with 115k, replaced the timing chain in it, and dropped it in my truck.

Lesson: regular TC replacement is a good idea.

 

I also replaced the clutch (original, with 184k; not bad, eh?). Just in time, too, I was almost into the rivets of the clutch disk.

 

have you checked the valve adjustments on the 'new' engine?

 

Yes, I checked the valves. All were good except for one exhaust valve that was a *little* open.

This AM I started the truck dead cold. It ran smoothly at 5 DBTDC with the pins shorted for 20-30 seconds. Removal of the jumper caused an increase in speed and an advance to about 12 deg. After it ran for a little while, it got rough and stumbly again.

I then swapped the throttle body from the original engine into the truck and I still get the stumbly unstable idle.

Is there any other sensor or component that may be bad on the 'new' engine?
Coolant temp sensor maybe?

 

It could be that, yes. Are you getting a CEL?

 

No CEL.

 

how long would you say a while it was before the idle quality tanked? and did it get progressively worse or just all of a sudden?

 

The first time it tanked, it was no more than 20 minutes after I had good performance. The odd thing is that it ran like that for a few minutes.

This AM, when I cold started it again, it ran well for less than a minute before it started to tank.

Both times it seemed to go bad pretty abruptly, but it could have taken as much as 10-20 seconds.

 

ran well for a minute then started going south and took about 10-20 seconds to go from best to worse....

okay, got two theories working in my head at the moment.
one is the coolant temperature sensor for the ecu may be sending improper signals causing it to think the engine is cold when it's not, or vice versa, and thus the mixture is getting whacked when warmed up.
the other isn't technically a problem- the idle air valve. It is working but the idle screw on the throttle body isn't adjusted properly. so when warm the engine is idling too low.

... edit- okay three theories-
the third is that the EGR valve is getting opened at idle after the engine warms up.