Engine Performance problem
1988 Chevy Corvette V8 Two Wheel Drive Manual 78000 miles
Recently I did some work on my corvette, including spark plugs, wires, rotor, distributor cap, adjustable fuel regulator, idle air temp relocate, new air filter, and air foil in the throttle body. After I put it all in and got everything back together. It would not run and I thought it was the timing. I followed the timing procedures in the maintenance manual I have and put it to 6 degrees btdc. The problem is that the engine still pops a lot. I Turned the engine off and plugged the Electronic spark control ground back in. The engine still ran at this point but it would hunt up and down and still would pop on occasion. I realized the MAF was disconnected and when I plugged it back in, it will not run at all. I spun the engine to TDC on cylinder one and made sure the rotor is pointing close to the proper location on the distributor. I have a friend who works at a GM dealership and told me how to check the MAF and it tested good. I have checked the routing of the plug wires and firing order at least 10 times and i'm sure they are correct.
Couple of things, when a car runs better when a sensor is unplugged as opposed to plugged in, that usually indicates somethings wrong with that sensor, If you know for sure that you tested it properly(maf sensor) then I would clean it if you havent already, then check the large hose coming off of the airfilter box, for any cracks and holes(vacuum leak). Also change the pcv valve, and check the mapp sensor, clean it out etc. Im also wondering if the fuel filter is clogged. Its something minute that is causing this problem, however those are usually the things that make us pulll our hair out trying to figure it out. Check these things and get back to me
November, 1, 2010 AT 9:47 AM
Is there a check engine light on?
November, 1, 2010 AT 5:49 PM
I replaced the PCV and did a pressure check on the fuel rail, 43 psi, and the minimum is 42. I want to replace the fuel filter but the nuts holding it on aren't budging. With luck I can get the new one on some time tomorrow. Just keeps starting and dying. I'll let you know what happens when I get the filter changed. One thing I was reminded of is that at one point while trying to dial in the timing I got a shock from the top of the plastic ignition coil cover. Could this be causing a short? Electrical is not my best area.
November, 1, 2010 AT 5:52 PM
And the only code its throwing is the one for the Electronic Spark ground being disconnected while timing, 44 if I remember correctly. When I had the MAF disconnected it had another but not since I plugged it back in.
November, 1, 2010 AT 9:17 PM
So no check engine light since everything had been hooked back up, and that electronic spark ground code went away right? If you have your own scanner just check again, just to see, if something was missed. And I will wait for your response.
November, 2, 2010 AT 6:57 PM
No codes at the moment. I know the timing is not dead on right now but it should be within a few degrees, so should run. I got the fuel filter off and the new one on as well but no luck in running.
November, 3, 2010 AT 9:29 AM
Ok how bout cleaning the maf?
November, 3, 2010 AT 9:33 AM
Try getting the timing right, also that code 44 is a oxygen sensor lean code, witch we know means that there is a fuel /combustion problem, and I still say 43 is too low for a v8 chevy corvette.
November, 3, 2010 AT 7:03 PM
I cleaned the MAF and adjusted the fuel pressure up to 48. With the MAF out I got the timing perfect then as soon as I plugged the EST back in it would not run. It will run when the EST and MAF are both out. But if either are in it will not run. I know the ECM almost never fails on these cars, but with my luck I wouldn't rule it out.
November, 4, 2010 AT 9:19 AM
Ok so we need to focus on the sensor, first test the plug to see if its giving the voltage, then check the sensors, get some of the spray cleaner for the maf sensor.