When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Okay, I replaced the starter, so now it's running again, but I'm still having problems. White smoke came out of the engine compartment near the rear of the left valve cover immediately after I started it. The smoke smelled to me like burning oil mixed with hot brakes. When I started it, I thought I heard a clunking noise. It seemed to rev a little high when it started, and would bog down like it was flooded if I touched the gas. All gauges on the dash read normally.
I removed and reinstalled the spark plugs, but I couldn't get the torque wrench on the #8 plug, so I just approximated with a breaker bar. Could a loose plug be the problem?
Here are a couple things that could be related:
- It had low oil pressure once it warmed up in the past, but I believe this was from fuel in the oil from a bad FPR diaphragm. Should be fixed now.
- When I bought it, the coolant was low.
- I replaced the fuel pump and filter.
Last edited by C4ProjectCar; 07-30-2014 at 06:59 PM.
Looks like smoke was just engine cleaner or something burning off the manifold. Also, the clunking noise is something in the dash. After a while of running rough with it "hunting" (I believe it's called) between 1000 and 1400 RPM. After it cleared up, it idled at 1900 RPM. Also, the engine temp rose to about 200 F just idling. Any ideas?
Last edited by C4ProjectCar; 07-30-2014 at 09:50 PM.
I adjusted the set screw on the throttle body and got the idle down to 1000 RPM. Normal is 650 RPM, right? I'm thinking the problem is either the IAC or a vacuum leak.
While idling at 1000, the oil pressure dropped down to the crosshatched zone on the gauge. Based on what I've read, the sensor is fine, but I'm going to have to hunt down a mechanical gauge to check. Where do you attach an oil pressure gauge to the engine?
When I revved it (it probably would have gotten to about 2.5 or 3k RPM) the engine backfired, but didn't do it again when I revved it.
So many problems with this car... Oh well, it's a learning experience.
I started it up again, and it started at 1000 RPM. It rose to 1500 as it warmed up, and I let it idle for 5-10 minutes. The oil pressure dropped to 10-15 PSI but didn't get any lower. I don't understand how it would go from dropping to 3 PSI to staying strong in the green. Can someone help me figure out what my problem is?
you didn't just turn that idle screw to adjust the idle did you...there's way more to it that that...you have to do the minumum idle adjustment to set the idle.....can't just turn the screw....
high idle can be a vac leak....spray some tb around the vac lines to see if rpm rises...I wouldn't worry about oil pressures until you get the idle correct....keep at it, once it gets running good, you'll be happy
I did turn the screw. The plug was missing, so I believe it had been adjusted previously to solve the low oil pressure at idle.
Yep, I plan to look for vacuum leaks as soon as I have the time.
What's TB? I'd heard to use carb cleaner.
Okay, I pulled engine codes with the ALDL. It threw ECM code 22, meaning low TPS voltage. Does this mean I have to replace the sensor, or can it be adjusted?
EDIT: Want to make sure I read the codes properly. I jumped pins A and G, then read off the codes that appeared. I read something about a manual mode at the end of the codes reading out, but I didn't think that was necessary.
EDIT 2: Bonehead of the year award goes to me. Seems I forgot to plug the TPS back in after I did some work. I'll update with how it runs.
Last edited by C4ProjectCar; 07-31-2014 at 03:06 PM.
Well, this is interesting. Now, running for less time than it did last night, oil pressure dropped down dangerously low. So sometimes it happens, sometimes it doesn't. And the engine was cooler when it happened than it was at idle last night.
I did turn the screw. The plug was missing, so I believe it had been adjusted previously to solve the low oil pressure at idle.
Yep, I plan to look for vacuum leaks as soon as I have the time.
What's TB? I'd heard to use carb cleaner.
throttle body cleaner.....you must do the minimun idle adjustment...you have messed yourself up turning that screw....then set the tps....it will not run correctly until you do...you're wasting your time chasing low oil pressures at idle. it's outlined in your fsm, there are threads explaining how to do it on this forum.....
throttle body cleaner.....you must do the minimun idle adjustment...you have messed yourself up turning that screw....then set the tps....it will not run correctly until you do...you're wasting your time chasing low oil pressures at idle. it's outlined in your fsm, there are threads explaining how to do it on this forum.....
Okay, here's where I'm at.
I went through the whole procedure (this link) to adjust the idle, disconnecting the IAC and EST cables. I skipped the step of setting the TPS because I read from several sources that 1990 and up have self-calibrating throttle position sensors. I only got it down to a base idle of 500 RPM (for a manual it should be 450) when it started clunking so I stopped there. It also was chugging below 1000 RPM. I finished the procedure, and ended up with an idle... exactly the same as I had before - 1000 RPM!
The oil pressure is still dropping to about 2 PSI. I haven't gotten a mechanical gauge yet because I've been fixing other problems, but I have noticed a couple things. The oil pressure light never comes on (it's the one on the instrument panel that says "low oil", right?) no matter how low the gauge goes. I believe the light should come on at 4 PSI, but I've seen the gauge at 2 with no light. Also, the needle on the gauge wavers, almost a twitch. Does this point to anything?
I bought a mechanical oil pressure sending unit and found that my sender was good.
Here's what I found:
When it heated up, it had oil pressure of 4-5 PSI at 1000 RPM. When I revved it to 2000 RPM, it would jump by around 20 PSI. I plan to drop the pan as soon as I get some ramps for it.
Do these symptoms point most to worn bearings, a stuck oil pump bypass valve, a bad oil pump, or something else? I am getting anxious to be able to drive my car so I'd greatly appreciate feedback; the sooner the better.
I bought a mechanical oil pressure sending unit and found that my sender was good.
Here's what I found:
When it heated up, it had oil pressure of 4-5 PSI at 1000 RPM. When I revved it to 2000 RPM, it would jump by around 20 PSI. I plan to drop the pan as soon as I get some ramps for it.
Do these symptoms point most to worn bearings, a stuck oil pump bypass valve, a bad oil pump, or something else? I am getting anxious to be able to drive my car so I'd greatly appreciate feedback; the sooner the better.
Common theory would point to worn bearings, as this is a classic symptom. However...
There are a couple of things about the LTx oil pump set up. First is the drive gear mount. It is anchored in the lifter valley with a plastic mount. These have been known to crack/break. This can cause severe wear on the gear at the very least. This happened to me.
The pick up in the oil pan has been known to fall off. This also would create a low pressure/starvation situation.
I have also heard tale of the pressure spring in the pump failing.
If your sending is good, then you have a low pressure situation. I personally would go ahead and get a new pump with a metal mount, as well as a new set of bearings. Hopefully this combination will take care of it.
Common theory would point to worn bearings, as this is a classic symptom. However...
There are a couple of things about the LTx oil pump set up. First is the drive gear mount. It is anchored in the lifter valley with a plastic mount. These have been known to crack/break. This can cause severe wear on the gear at the very least. This happened to me.
The pick up in the oil pan has been known to fall off. This also would create a low pressure/starvation situation.
I have also heard tale of the pressure spring in the pump failing.
If your sending is good, then you have a low pressure situation. I personally would go ahead and get a new pump with a metal mount, as well as a new set of bearings. Hopefully this combination will take care of it.
Thanks for the info.
It is an L98, which is the previous gen to the LT1. I noticed you said "LTx", so does that matter?
For someone with fairly limited mechanical expertise (I've bled brakes, replaced a starter, changed spark plugs, etc, but nothing major), how many hours of work would you estimate that to be? I assume changing bearings requires pulling the engine?
Last edited by C4ProjectCar; 08-05-2014 at 03:33 AM.
Your high idle could be caused by a bad CTS (Coolant Temperature Sensor), the one on the front of the intake manifold. A bad connection or broken wire can also cause this. If the ECM thinks the coolant is cold it will advance the idle speed (like the old fast idle mode on carburetors).
You can test the CTS by disconnecting the connector and measuring the resistance of the CTS. The resistance should relate to the coolant temperature per this chart:
Your high idle could be caused by a bad CTS (Coolant Temperature Sensor), the one on the front of the intake manifold. A bad connection or broken wire can also cause this. If the ECM thinks the coolant is cold it will advance the idle speed (like the old fast idle mode on carburetors).
You can test the CTS by disconnecting the connector and measuring the resistance of the CTS. The resistance should relate to the coolant temperature per this chart:
Hmm, I'll check that out.
How do I measure the temperature to compare to the resistance?
07-30-2014, 06:56 PM
