Problem with my SHO - Please help

[ToddL]

I have a 93 ATX and it recently started giving me problems. I have problems starting it and when it's running it won't idle and sounds like its running on only a couple of cylinders. I found that if I can get it rolling I let it rev up around 4000-5000 RPM and something frees up and the car goes back to normal. It runs great until I shut it off and let it cool down. Then when I restart it I have the same problem. Any ideas what the problem could be? It did this a couple of times and the problem went away, but now it's gotten worse and happens more often. It's getting harder and harder to start. I checked the codes a couple of times and got different readings each time. The codes I got were for the MAF reading too high or short to power and that both O2 sensors are lean. I'm going to clear the codes, run the car and recheck the codes a couple more times to see if I get the same ones. Does this sound like an MAF or O2 sensor problem?

 

[Two93SHOsguy]

I have 2 93 ATX SHOs, one running very badly. Because of the info in this forum, I checked the sparkplug wells (just pull the wires out) and they were almost full of engine oil (That is, the 3 accessible plugs on both cars!). I am replacing head gaskets and o-ring seals, plugs, wires, and O2 sensors on the one that runs poorly, and I just got the oil out of the wells on the one that runs okay by using strips of flannel rag and a screwdeiver. I have heard that oil in the wells may not throw specific CE codes, but will cause erratic performance.

<small>[ March 30, 2002, 09:43 AM: Message edited by: Two93SHOsguy ]</small>

 

[nc89sho]

acctually you'll need valve cover gaskets and plug well seals, not head gaskets. felpro sells a kit. but i as to the first post, your problem could have something to do with the maf, because when the car first starts the computer runns in "open-loop" mode where it's not takeing info from the o2 sensors at all. this happens during the warm up phase and the only lean/rich info the computer has comes from the maf.

 

[luigisho]

Todd, if there is no oil in the plug wells then you are on the right track, but check these first. Clear the codes and see what pops up again. If you unplug the maf and it runs better (it will go to default setting) then I would suggest that is the problem. I would also suggest you clean the maf and act sensors to see if that helps.

 

[luigisho]

Todd, you should check for oil in the plug wells (even the back ones)first. If they're clean then clear the codes and see what pops up again. If you unplug the maf and it runs better (it will go to default setting) then I would suggest that is the problem. Also since it's cheap and easy I would also suggest you clean the maf and act sensors to see if that helps. Try these and if there is still a problem check back.

<small>[ March 30, 2002, 10:59 AM: Message edited by: luigisho ]</small>

 

[ToddL]

I checked the plug wells and they are all dry. I had replaced the gaskets when I did the 60,000 tune up about 5,000 miles ago. So it's probably the MAF. I tried unplugging it and it made no difference, so I'm not sure. I'd hate to replace it and have that not be the problem. Most parts stores won't let you return electronic parts once they've been installed.

Thanks
Todd

 

[sdpatt]

Todd,

If both O2 sensors are reading lean, the engine probably is running lean. The chance that both sensors fail simultaneously in the same manner is remote. The MAF error could be the cause of the lean condition. Cleaning the MAF elements won't change the error code since you said it was an electrical fault rather than a signal out of range. What exactly were the codes?

Since you have had the intake manifold off for the 60K work, you should check the ground path to the DIS module. It is normally essential that this component be well grounded. Check the ground strap to the upper bolt of the passenger side, rear intake manifold bracket. Also check the two 12mm bolts that secure the intake crossover tube to the front and rear intake plenumns. Now check the four fragile 5.5mm (7/32") screws that mount the DIS to the crossover tube. You should also check the torque on the intake manifold-to-head bolts (17 lb-ft) and for vacuum leaks.

Check the following vacuum lines.
 One 1/4" vacuum hose and one 3/8" crankcase breather hose on the top forward face of the throttle body
 One 3/16" vacuum hose on the fuel pressure regulator
 One 5/8" vacuum hose on the passenger side rear of the intake plenum
 One 3/16" vacuum hose to the secondary intake runner valve vacuum accumulator
 One 1/8" plastic vacuum hose on the exhaust gas recirculation (EGR) valve (3.2L)
 One 1/8" plastic vacuum hose on the EGR pressure sensor module (3.2L)

Check the following electrical connectors.
 Two to the distributorless ignition system (DIS) module on the intake crossover tube
 One to the idle air control (IAC) valve
 One to the throttle position sensor (TPS)
 One to the mass air flow (MAF) sensor
 One to the solenoid on the vacuum accumulator (black plastic canister)
 One to the EGR pressure sensor module (3.2L)

 

[V6&V8SHO]

uh oh Sdpatt's breakin out the check list. He means business! thumbs_u