I have a 96 2.4l z24. It ran down a flooded road and took on water. When I opened it up, the intake manifold had a signifigant amount of water in it. There was water sitting on top of the intake valves on one cylinder and the plug was wet. There was no standing water inside of the cylinder. I have torn everything apart, and gotten it back to working condition. BUT, I have a rough idle, high negative fuel trims (around -25stft, -8ltft) at idle, and the vehicle wants to stall as soon as it enters closed loop. This is a last ditch effort to figure out what is wrong with it. These parts have been replaced - fuel regulator, o2 sensors (up and downstream), MAP, cam sensor, fuel injectors, ignition coils, plugs, wires, IAC, intake manifold and throttle body gaskets and EVAP solenoid. These parts have been checked out - throttle position sensor (which shouldn't factor in at idle), timing chain, vacuum lines and EGR. I have done a compression test. DRY 1=210 2=190 3=150 4=180. WET 1=210 2=200 3=200 4=210. The engine sounds like it has a fairly consistent misfire. I can't find the source, I hear it in the exhaust. No codes. Prior to changing some parts, I threw a code for Bank 1 Rich. But I've been at this for soo long that I couldn't tell you what part fixed that for me. I am concerned that with water in the cylinder it raised the compression ratio and cracked a ring or two. That could allow unspent fuel into the crankcase and back through the PVC line into the intake. However, unhooking that line does not affect performance or fuel trims. DEAR GOD, PLEASE HELP ME!!!
What kind of scanner are you using? handheld? a computer DIS system monitoring your engine would be able to show you better where things were going wrong, especially that misfire that won't throw a code for a regular scanner, not sure if you have access to that though.. usually more of a dealer thing without spending alot of money.
My scanner is a handheld Innova. Unfortunately, no access to a better tool. It's not a bad DIY scanner, but lacking.
I don't have any answers...just more questions.
the high compression pressures and the max/min difference at 20%...i know manufact spec allow 30%. don't know if i would rule out mechanical until a leak-down test is performed.
when warm does it have a long crank time to start? Does it crank over slow?
misfire...if its there consistently you have to isolate it to a cylinder if possible. Since your scan tool can't show misfire data; perform a power-balance test.
did you clear the map vac line of water during replacement of the map?
how high did the water level get?
I don't have the equipment for a leakdown test, yet. I've seen simple diagrams for making a tester. That will be coming. When warm, the crank time is quick and hasn't caught my attention. When cold, it's no longer than I would expect. The MAP vac line, is very short and was definitely cleared of water. As far as the water is concerned, I'm not quite sure what you mean. The intake manifold was about 1/3 full of water. Water had entered at least one cylinder, and although I didn't see any water in the cylinder, there was water between the electrodes of the plug. I am not sure how to go about a power balance test due to the fact that the ignition system is directly above the spark plugs and I cannot remove them one at a time as the engine is running.
The coil cover is a suspect...
Coil cover has been swapped, no effect. Built a leakdown tester, waiting on the compressor later this week.
I am not sure how to go about a power balance test due to the fact that the ignition system is directly above the spark plugs and I cannot remove them one at a time as the engine is running.
some options if you want to do this:
you could power balance by disonnecting the fuel injector harness if its easily accessible.
second option is to lift up the coil assembly....attach short pieces of windshield washer tubing to the coil towers (this is conductive and will allow you to short out the cylinder by touching a grounded test light to the tubing). attach four old spark plug wire to the spark plugs and place the other end of the spark plug wires over the tubing.
start the engine and ground out each cylinder with a test light.
Power balance test is next on the list. I will be changing my buddies plugs and wires in a day or two and will use the plug wires. If all else fails, the injectors are easily accesible. This isn't over yet. I really do appreciate the suggestions, please keep 'em coming. Will update in a day or two. Thank you
The girl has been driving the car periodically. It took a 120mi round trip to school, around town to work and back. She says it's acting funny. I am pulling codes for O2 Sensors now. One set and one pending. P1133 and P0141. I have replaced both of these sensors with new. Why am I seeing these codes?
I don't see any signifigant changes in the engines behavior when doing a power balance test. I did it using the fuel injectors. The compressor is here and I'll try a leakdown test this weekend.
