First off, I want to say hi as I am new here and just purchased my 89 pickup a week ago, this board has been a great resource for me already. The truck has a few issues but I got it for a great deal, $500 with toppper, CD player and a extra set of rims with misc 31's on it.

I've done quite a bit of tune-up stuff to it and it is running a lot better but I just failed my emissions test, HC was very high, every other parameter was quite a bit below limit. From what I understand high HC is typically unburned fuel. I might have an intake leak, but if so I haven't tracked it down yet. I made sure to drive the truck on highway for ~20-30 minutes before the smog test so it was plenty warm.

My other issue is on idle, not sure whatÆs going on but when I apply my brakes the idle cycles really low and gets close to stalling until the ECU brings it up again. It cycles like this and stays idling but it is really rough.

Things I have done to my '89 22re 4x4 with 210k miles
-Set timing to 5 deg. (Did this last night after E test fail, timing before was pretty advanced, maybe this is the cause by itself)
-Cleaned EGR vacumn modulator (have not checked egr yet) (Did this last night after smog test fail)
-Used about 3/4 can sea foam through intake tract, other 1/4 in oil. Also put a full can in with 14 gallons of gas.
-New Wells distributor cap and rotor
-Corrected the gap on the spark plugs to .031", plugs aren't new but do not look fouled. (Did this last night after smog test fail)
-Removed silencer section out of air box for air filter. Air filter isn't new but is not too dirty. I have also shaken out the filter to remove any dust etc.

I am not sure what RPM the idle is, as the truck has no tachometer. Maybe the idle is too low?

Is this normal for idle to drop when brakes are on?
The cat might be original, it looks like it and it makes more cool off tick noise than any other converter I've had/used. I was thinking about changing it but I donÆt want to just throw $ at this truck.

Todd

Idle is too high if it cycles with brake application. Turn it down into the 750-900 RPM range. Higher than about 1000 and the ECU will cut fuel to the injectors until the RPMs drop below that level then it'll speed up again and the cycle repeats. Check the Throttle Position Sensor, make sure its reading properly at idle. Also, when you set the timing, was the diagnostics jumper shorted? If so, did you see the idle speed and/or timing change when you did so? If not, its likely the TPS idle setting is not correct. High HC is unburnt fuel = too rich, I would check the O2 sensor.

Okay thanks for the input 4Crawler.

I did short the diagnostics jumper (T1 to E1) and verified that the check engine light came on and blinked steadily when I did the bridge. Actually I didn't really see a change in idle, not sure about timing since I only put the light on it with diag shorted and after to verify advance with vacumn.

Checking the O2 sensor is a good idea, will do.
Could bad injectors be a possible cause?

Update

I tested the TPS and it was not adjusted correctly, so I went ahead and adjusted the TPS, BTW that bottom screw is a PITA to get to. After adjustment I had much better driveability, maybe a bit more power, I dont think wide open throttle was affected but partial throttle definitely was. My idle is quite a bit better too. The motor heats up quicker as well, this should indicate a leaner mixture which would be good as I have been running extremely rich.

I'm going back at lunch today to get my emissions check, I'll be adding some denatured alcohol to the tank today and then going for a drive to heat everything up hopefully I pass.