Hi everyone -

1991 22-RE Pickup Base, 199k miles

Recently I started having issues with the idle. At first, the idle was remaining high (1500 rpm or higher) even with the car warmed up and the idle would bounce up and down at stoplights if I depressed the brakes. I eventually tracked this down to a faulty Idle Air Control Valve and replaced that which allowed me to lower the idle to the standard 750-800 and set the ignition timing correctly. However, now the truck idles too low when warmed up. The truck will shake and sound like it is about to stall. I can adjust the idle with the idle set screw, but unless I have it at 1200+, the truck feels like it wants to die. At cold start, it runs great, but as it warms up it gets worse and worse. It sounds like its chugging almost at idle - not sure if its misfiring or not but it definitely does not sound right. I was also getting a bog/stutter under load before which is what triggered me to start solving this issue. That seemed to have gone away for a while but it did do it a few times today when I drove it in the morning before setting the ignition timing again. Hasn't done it since but I'm not sure if that it fully resolved yet either.

I did build a DIY smoke tester with a soldering iron to look for vacuum leaks but I could not find any. I did a vacuum test a few weeks ago it was in the normal range, if not a bit high. I did a compression test about a year ago and I had good compression (about ~170 psi across all 4 cylinders with less than 5 psi variance). The only thing I did before this issue arose was I did a leak-down test which involved me pressurizing the engine. Is it possible that that did something? It didn't do it until a few days after though.

I've done the following recently:
Timing Chain replaced @ 196k
Fuel Filter replaced @199k
Throttle Body cleaned and gasket replaced @199k
Valves Adjusted to .008" and .012" at @198k
TPS adjusted using multimeter @ 199k

Any ideas what this could be? I'm getting frustrated and I miss driving my truck.

 

Are you blocking vacuum advance hoses when setting timing? Maybe leading to dropped idle?

My 94 22re (212k miles) shakes at idle a bit, hangs around 750-800RPM, 4° BTDC. I did have similar issues while playing with my timing (forgot about the vacuum lines)
I'm running a redline 261 cam, header, 2.25" exhaust, and an AFM I got from a 3vz truck, may be why it runs best at 4° not totally sure.

Maybe try setting timing at 6° see what happens

 

Vacuum advance lines on a 22RE????? Come on now.....

 

...the vacuum lines coming off the distributor........or am I using the wrong phrase?

 

There are NO Vacuum lines that run to the distributor on a 22RE

Fuel injection and all electronic timing advance. No vacuum advance on 22RE

 

Sorry about that I was thinking of the power steering vaulve.....

 

No need to block off the vacuum lines on the power steering pump when setting your timing.