Help! 1992 Corolla Running Rough - Pre-1997 Toyota Corolla and Geo Prizm

I just put the engine back in my 92 Corolla after a much needed reseal. I plugged in everything I can see and it looks as though everything is back in its place. The car will start and run but it runs extremely rough. It has an extremely erratic idle, it will rev up to 2500rpm then go down to 500 then back to 2500. Just Vroom...Vroom...Vroom... Then when I apply any amount of throttle it will rev up to almost 5000rpms and then come back down. Even if I just barely tap the throttle.I didn't go deep in the engine, or remove the timing belt when pulling it. Essentially just pulled the engine out and put it back in. I did replace both exhaust and intake manifold gaskets as a part of the reseal.

I have checked for stored codes and there are not any. The check engine light just flashes continuously. I have gone through and made sure every vacuum line is connected and every sensor is plugged in.

Any suggestions or advice would be much appreciated.

Thank you!!

Erratic idle is pretty much a hallmark of a vacuum leak, though a flashing check engine light indicates a misfire situation. This engine the fuel injected one or the carburated version? Given the model year, I'll assume you have the fuelie variant.

Did you double check the EGR setup? Around the intake manifold and throttle body? PCV system, EVAP system? Everytime I pull an engine - I always forget one or two connections - just inevitable it will happen. Stuff can get pinched or you might introduce a new leak (stretched hose, cracked hardened hose, etc.).

How about the ignition - firing order? Did you pull the plugs and see how they looked? Did you verify timing, even though you didn't mess with it, good practice to double check?

I have checked timing, I have pulled spark plugs, and I have tried pulling vacuum lines and switching them around.

I still need to do a real vacuum leak test so I'll do that. I also need to bleed the coolant.

Also, I am getting weird puff noises and small plumes of smoke, kind of like a small backfire. Every 20 or 30 seconds there will be a puffing noise, the engine will jump slightly, and there will be a small plume of smoke around the exhaust, intake manifold, or fuel rail. Any insight as to why that is happening?

If you can feel something puffing out around those areas - then that would pinpoint a possible leak. A periodic puffing/huffing noise from the engine, especially at those time scales is generally a sign of a bad or dying IAC valve. IAC = Idle Air Control - for this year could be either a vacuum actuated or electronic solenoid (1992 was a transition year) actuated valve. That would definitely cause the see-sawing idle behavior.

Of the two types, it would be either a rotary electronic solenoid type IAC valve controlling the fast idle and idle speeds or a duty control VSV type IAC valve that regulates air volume bypassing the throttle valve to control idling speed. Both are on the throttlebody.

Could also be a EGR Cut–Off control system in with the EGR is cut off under light engine loads or low temperature conditions to maintain drivability / idle speed.

EGR is more likely to be affected by an engine pull - if you dent the tube that run under the EGR valve or forget to hook up any number of those hoses - it would start acting erratically. The IACV is a little more robust, but even small issues (little bit of grit gets in there, engine sat for an extended period of time (varnish will gum that valve up in a heartbeat - with the ethanol they add to gas, only take a couple of weeks to start building deposits).

Update.

Just did a vacuum leak test and found that when I spray starter fluid near the intake manifold gasket the engine idles up. If I spray a constant spray at it the engine will idle up and stay at a high idle. So I pulled the intake manifold off again and it turns out there were chunks of the old gasket still left in between the new gasket and the head. So I cleaned the surface, put everything back together. I started it up and it seems to run much better now.

BUT, there is a much larger problem now. When I put the car in gear (drive) it took a tiny little move forward, maybe 5 inches then stopped (could have just been rolling). I put it in reverse, take my foot off the brake and nothing happens, no movement. I put it back in drive and it doesn't move at all. It does even feel like the transmission is engaging when I shift it into gear.

Any suggestions will be greatly appreciated!

Which transmission is in the car - 3-speed A131L or 4-speed A240L transaxle? Did you split the transaxle from the engine when you pulled it or did you pull it as a single assembly?

A number of things can cause a vehicle to not move forward/reverse:

- Shift cable could out of adjustment

- Valve body or primary regulator faulty / no or low fluid level

- Parking lock pawl could be faulty (unlikely, especially if it worked before)

- Torque converter clutch faulty (unlikely, especially if it worked before)

- Converter drive plate broken or clearance not set (only when you split them)

- Clogged oil intake screen blocked

- Drive axles could be binding / installed incorrectly

- etc.

I separated the engine and transmission when I pulled them. I believe the car has the 3 speed transmission but I'm not positive. I left the shift cable, and axles in when pulling the engine out. Basically nothing came off of the transmission. And everything did work before.

However, I did have some issues with the torque converter when pulling the engine. It got bound up on the flex plate and I had to pry it off. I sanded it down and it seemed to go on fine when I put it back together.

Also, the fluid level in the transmission looks good.

Sounds like the TC didn't get fully seated or the flexplate got bent. I usually try and mount the TC in the transaxle and hold it there as I mate the transaxle to the engine. Then tighten the bolts to the flexplate through the access hole on the transaxle case.

Sometimes just splitting them apart and bolting them back together works. Before you go though all that trouble, I'd double check that it isn't a linkage issue first.

How can I check the linkage? Just watch the shift linkage when I shift gears?

Yup, have someone help out if possible - move the shifter through the detents while observing that it is actually moving the lever on the transaxle. If it is, then it most likely points to a TC seat issue.