skoebl

I've done a bit of searching and just wanted to make sure I understood what I had read.

I have a starting/idle problem (don't we all). The previous owner had done a terrible job of half removing the emissions; so I completely removed them (as per the guide on rotaryresurrection.com). After doing that it ran a LOT better (in that it would actually start). But, now what it does when I start it is rev up to about 2200 rpm, stay there for about 15 seconds, then die. If I keep my foot on the gas it will stay running around 1000 rpm, but it will buck and backfire and make all sorts of fuss.

I have checked all the areas for possible vacuum leaks and have found none. Am I right in assuming that this is a TPS problem?

(BTW it's an 87 n/a base model)

Icemark

Nope, sounds like it is missing the cold start assist thermovalve. They probably removed it when they removed the emissions or did the throttle body mod.

skoebl

Ugh...is there any way to make due without it?

Icemark

Yeah, hold the throttle open to 1000-1500 until the engine is warm or get another and hook it up.

pfsantos

iTrader: (1)

You have a couple (more?) of issues. When cold, the fact that it doesn't go to 3000 RPM is as Icemark said - Air bypass valve (the one near the rear on the driver's side of the dynamic chamber). You are probably also lacking the BAC valve to the front of the Dynamic chamber, driver's side, which usually has a coolant hose front and rear. This won't help the engine compensate for electrical loads and react to sensor inputs to adjust idle.

I suspect your bigger problem, when warm, may be a vacuum leak, lean mixture, or out of adjustment TPS.

When it's idling high and roughly while cold, remove a vacuum hose after the throttle body (there should be one, for example on the lower intake - wait a minute - if you did the emmissions removal, you know this ****). See if it idles worse. If it doesn't change, you have a vacuum leak. You can also leak a bit of propane from a bottle near the intake and fittings to check for vacuum leaks.

Lean mixture - kind of like a vacuum leak - can be caused by someone messing with the mixture adjustment screw near the Boost sensor.

TPS - obvious...I guess you know how to test it...in the stickies or archives. Note that you want the engine to be warm enough to move the fast idle cam away and let the throttle close completely. Only when this happens can you set the TPS properly.