First off, thanks to everyone here. I didn't ask any questions, but then I didn't have to. All the information I needed was just a search away. So thanks to everyone who contributes!

I bought a '96 DI about a month ago. I think I got a pretty good deal, but it definitely has some issues. The biggest one so far was the idle. The problem was, it didn't.

I popped the hood and found the vac lines going to the throttle were dry rotted and broken in places. I replaced those and it ran a little better.

I then cleaned the intake and MAF with carb/intake cleaner and it ran a little better, but it still wouldn't idle.

I replaced the IACV with the ACDelco part (huge thanks to the forums) and now it mostly idles.

Here is the issue I'm still having:

Once the engine is warmed up (coolant temp ~185 f, thanks UltraGuage) the idle at a stop in Drive hovers right around 600 RPM (UltraGuage FTW), but occasionally it will drop down close to 500 RPM and the low oil preassure light flickers. If I blip the throttle it will go back up to around 600.

Any thoughts on what I should check next?

Thanks again!

edit:


I've also checked the plugs and wires and they're perfect. I'm am throwing two codes, one for the CAT, no voltage, and one with no descriptions. MAF, O2 1 and O2 2 seem to working correctly with a max of 1.2x.

 

Oil pump pressure test with a manual gauge. If cracked, pump can make pressure, just not quite enough. Spec is 10 PSI at idle warm and 40 PSI at 2500 warm engine. You could also have oil sludge. Good oil to run this time of year is Shell Rotella 5W40 (syn). Widely available. You can borrow/rent test gauge at many auto parts stores.

An engine hickup should not drop oil PSI to under 7 pounds, which is about where the switch turns on the light.

Might want to also check your fuel pump PSI, schraeder valve is on passenger fuel rail, expect 32-34 PSI.

And you'll be needing to resolve the code issues. Could you post the numbers?

 

Seafoam to clean the intake. You cleaned MAF, but still need to clean the inside. Carb cleaner will not do, Seafoam and follow the instructions on the bottle carefully. It worked for me.

 

Mine also idles in drive in the 600-650 range, but occasionally drops into the 500's as you said. Is this normal for your other guys too?

If it's been a long time, changing your oil filter too wont hurt. Just make sure to fill it with oil before screwing on.

 

My point is that while idles dip for one reason or another, there should still be 7 PSI of oil pressure. I'm skeered of the dark, but I'm more skeered of an oil light....

 

Agreed. My oil light never comes on, even when RPM dips. I was just wondering if his/my RPMs were normal for everyone else too.

 

Thanks for the comments! I should have thought of it, but I believe an oil change is definitely in order. The previous owner, while a mechanic, seemed to neglect this one of his dozen cars.

After the oil change I'll do the pressure test if there are still issues.

I'm a bit hesitant do an engine flush (Seafoam?). From what I've read it can eat push high milage gaskets over the edge. The chassis on my DI had 235k when the engine was replaced with one that only had 73k on it. The odo wasn't hooked back up so I don't know the actual milage.

 

Ok, my engine codes are P0300 and P0305. I know one of them is the cat. Need to research if I can pass emissions with that one or if I need to head to the junk yard. Hell, I haven't even bothered to see if there is a cat. The exhaust is clearly aftermarket and quite loud.

 

and in this case google is my friend. random misfires, cylinder 5. I'll re-check that plug and wire tomorrow. Anyone know a good way to test the coils?

 

swap coils to see if problem follows

P0300 is multiple misfire, not caused by damaged cat, but can result in damage to cats.