Hello, Once again I am in need of your help. There is something wrong with left side of the engine 5-6-7-8 car is Euro 2.7 motronic. Changed the belts and did a major this March and car worked like a charm. Than I went to approx. 300km Sunday drive and on the way back it started missing sparks on one side. If you push really hard it works, but only sometimes. Last week I went for a short test drive and saw that complete left side cat and can pipe gloves red. of corse my idea was that one of the cats failed -Measured LMM both sides OK -Changed spark plugs 5=white 6=black and wet 7=black and wet 8=white -checked all connections (seems ok) -changed both cranck sensors -checked all wacums -Injected 2 cans of lmm cleaner -took the catalytic converters off and they are both intact (you can see thought) -disasembled rear exhaust can to see if it had collapsed, but it is intact. Car still runs like Sh.t and 1-2-3-4 run fine while 5-6-7-8 miss a lot and complete left exhaust still glows after only 5 min of running -If I unplug LMMs it is the same. -If I unplug lambdas it is the same. My next step would be to check fuel pressure and injectors change coil from left to right and than change computers from left to right than I am out of ideas. This year the saga just doesend stop Any suggestions?
Just a guess, but I think I would check the fuel pressure regulator on the bank that's glowing red-that's probably a lean condition on that side, and I think the most likely thing that would cause that is a stuck open FPR.
I think the first step is to take off the cat and check it first. It may be plugged causing the red glow. If clumps of honeycomb shake out it is done. You can drive the very loud car with open pipes and see if the miss goes away or test it with a scantool like a digitech meter. You can't do any diagnosis with wiped out cats and you will never get the car to run right. If the noise kills you then tack weld in a straight pipe just for test purposes and then do the diagnostics.
If it were my car, I would: 1) Check the compression on at least the two cylinders (6 & 7) that have black/wet plugs. If the compression is low, you're wasting your time looking for other problems. Could be a head gasket blown between two cylinders? 2) If the compression is OK, I would replace those two plugs with new ones. Don't bother to try to clean the old ones. 3) Before restarting the engine, I would check the oil. If two plugs haven't been firing, you may find that the oil is contaminated with raw fuel. Not good. And the cylinder walls may have been washed down with raw fuel. Not good. 4) If the compression is OK, and the plugs are good, then you might have a bad ignition coil, or bad plug wires, or injectors that are stuck open. Several possibilities. Don't push your luck with overheated cat converters, they get VERY hot . Hot enough to burn your car to the ground. Good luck!
Glowing red hot exhaust is an indication of lean condition, not raw fuel-that would create a cooler condition. Lean-lack of fuel=lack of fuel pressure or clogged injector(s)
I'm always willing to bow to greater knowledge and experience than my own, but in this case I don't think I agree with you. UNBURNED fuel in the exhaust system may actually have a cooling effect, but if raw fuel is igniting inside the catalytic converter, isn't that going to make the converter overheat? And he has reported two black/wet spark plugs, which seems like an obvious indication that raw fuel is being dumped into the exhaust. If it was a mixture problem, or an OXY sensor problem, or a fuel pressure problem, wouldn't all of the plugs on that bank have the same appearance?
Hello guys thanx for quick response. -Cats are ok. They vere taken off and inspected (all ok) -Spark plugs new I agree with plugzit, because also racing cars with bang system use gassoline without spark to cool down hot engine. Will switch fuel pressure regulators and check if glow effect changes sides. If it doesent I will meshure compression. And after that Injectors. Will post on my progress. Cheers.
we just got done doing a major service on a 348. the car sounded like an american muscle car with new parts. Hook a fuel pressure gauge up to one side of the bank and let engine idle. Ideally you want a fuel pressure gauge that will allow you to run the motor at the same time it is hooked up. hook the gauge at the in port of the fuel rail (towards the rear of the motor) pressure should be around 50psi. if you unplug the vacuum hose (at front of intake plenum) for the regulator the pressure to increase to 60psi. this is an indication the fuel pressure regulator is working. One thing we saw was when we took the fuel rail and injectors out and tested each one with an injector tester that turns the injector on, two injectors were not atomizing the fuel and were not flowing the same amount of fuel as the rest (was flowing less). To get a baseline of how each injector flowed, we had the engine off and bypassed the relay for each fuel pump and had to pressure rise to 50psi. at that point we turn the fuel pump off and tested the injector. monitoring the pressure difference from when the injector started (50psi) to when it stopped (about 15psi) we compared injectors to each other. By changing just these two injectors the motor ran like it should and sounded like a ferrari. It is a pain to go through each injector and test them but atleast you will be able to eliminate if that is the cause of your problem. You can also change MAF sensors which will cause problems with how the motor runs.
Also, fuel in the regs vac line = regulator death. I don't believe in testing injectors. Instead I believe in complete servicing and cleaning of injectors during the 30k service. Excessive? maybe but I think the results are worth it. These cars run amazing when the electronics are good thanks to the SRI helms gold kit and the fuel can flow as designed. Pumps fouled goop (serch Ernie's fuel pump rebuild thread) and 20 year old clogged injectors seem too often ignored. Half the people who want power adders don't even have a decent running platform.
