Engine Multiple engine codes

TTSaleen05 · Sep 7, 2019

I have a 91 LX 5.0, all stock except the BBK CAI, Shorties and full exhaust no cats. Symptoms are rough idle(sounds cammed), if I give it a little gas it will jerk/stumble/sputter then stall if I keep at it. If I go full throttle it can rev up a little bit. I can’t even drive it, I’ve been chasing this problem for almost two weeks. I pulled the codes: KOER-12, 21, 26, 33, 42, 92, 18
KOEO-11, 63

Things I tried so far:
Code 12-I swapped the IAB, its getting voltage, cleaned contacts, new tps calibrated to .98, it’s getting the 5 volts
Code 21-cleaned the ECT, cleaned contacts
Code 26-New MAF, tried different clocking positions, cleaned contacts, it’s getting 12 volts, ground is good, resistance is good To the pcm connector.
Code 33-EGR getting voltage, diaphragm is good, even blocked off vacuum line to rule out leaks, swapped EGR
Code 42/92-checked FPR for leaking fuel;good, fuel filter, fuel pressure good; used gauge at valve between 30-40 psi at idle with vacuum line off, injector voltage good, used stethoscope to listen for clicking it was good, checked ohms on injectors; all are the same, back probed pin at ecm 43&29 for 02 sensors;reading between .2-.9, cleaned contacts for 02 sensors. Fuel pump sounds good when key is on the on position.
Code 18-timing was advancing with spout connector in, timing set at 12 degrees, check the wire with the 22k resistor to ecm connector is all good, changed wires, distributer, TFI module, checked all ground especially the one near the battery, changed cap and rotor. Checked the resistance for the TFI connector wires to the ecm harness and all checked out. Also ok apart the salt and pepper shakers, spread the pins a little bi for better contact.

I’m getting a proper charge from the alternator, I’m stumped guys. I pulled the plugs and noticed they were pitch black. It’s definitely running super rich, pretty much sucking the fuel like crazy. Now when I first acquired the car, it had a bad TB gasket and you could hear the hissing. Since then I fixed the leaks but surprisingly, no change in idle or drivability.

TTSaleen05 · Sep 8, 2019

Anyone?

JD1964 · Sep 8, 2019

Since you’ve owned this car, has it ever run right? I’m trying to determine if you acquired a car with existing problems, or, was it previously running good but later developed problems.

TTSaleen05 · Sep 8, 2019

That is correct, since I’ve owned the car. It had the same symptoms and no matter what I did or replaced. No change whatsoever, I figured it will be an easy fix. I owned mustangs all my life, so I presumed it will be a project I can tackle on my own. Boy was I wrong

JD1964 · Sep 8, 2019

Do you know for sure how many miles are on the engine, not the odometer, the engine ? And, has the engine ever had any internal or mechanical work done on it?

TTSaleen05 · Sep 8, 2019

I cannot say definitively, I know the previous owner said he bought it to a shop to get some work done to it. However he claims he does not remember what work was done. All he could recall is that the shop said fuel was leaking into something. He then, according to him, got the car back and it drove great for 6 months then the symptoms started to happen again. That’s when he put it up for sale and I purchased it.

JD1964 · Sep 8, 2019

A higher mileage engine can have a timing chain jump a tooth. With the resulting severely retarded cam timing comes low compression, low vacuum. Poor combustion and excessively rich mixture happen with this condition.

Before I’d do anything else, I check cylinder compression and cam timing.

TTSaleen05 · Sep 8, 2019

Looks like I have to go to harbor freight to get some tools. I did check the timing with the light. It’s showing right at 12 degrees with the spout out. Would it still show that with a jumped tooth? And would it throw those codes as well?

JD1964 · Sep 8, 2019

A mechanical jump of the timing chain would affect the ignition timing setting. But, you don’t know if the distributor was adjusted after the fact. If it was, the ignition could read correct but you could still have severely regarded cam timing.

TTSaleen05 · Sep 8, 2019

Ok so pretty much, I should start gaining access to the timing cover to inspect the chain. Well I will dive and get started.

JD1964 · Sep 8, 2019

Cam timing that is off can be checked without pulling the front cover. This is done by using a dial indicator on the rocker arm of #1 cylinder. So, pulling the passenger side valve cover is all that’s needed. And getting a good view of the timing marks on the balancer. Which brings me to another idea. The two piece balancer on the front of the crank could have slipped too. That will throw off your ignition timing setting and can cause problems related to your descriptions.

TTSaleen05 · Sep 8, 2019

OK, I’m going to go out right now and disconnect the coil wire. I will try cranking it and monitor the balance or pulley

JD1964 · Sep 8, 2019

Compression check would be the first thing I would do. Poor cam timing would cause low compression across all cylinders consistently, minus any leaking valves or head gasket.

TTSaleen05 · Sep 8, 2019

The balancer appears to be fine, I had my son crank it over while I watched the pulley. I don’t have the compression kit to do the test yet. I even attempted to t the cylinder balance test but the engine barely goes over 1000 rpm. Which I think that’s why it’s throwing code 12

TTSaleen05 · Sep 8, 2019

I got the upper intake off, just to check for vacuum leaks. All looks good, I’m going to take off the lower intake to check the gaskets while I’m at it. Just burning time until I get the compression test kit.

jrichker · Sep 8, 2019

You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money. It includes how to dump the computer codes quickly and simply as one of the first steps. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix.

It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 250,000 hits, which indicates it does help fix idle problems quickly and inexpensively.

TTSaleen05 · Sep 8, 2019

Thanks richker, I’ve been scrolling through that thread tryin to a find a fix. The sucky part about it is that I can’t do a cylinder balance test. It barely gets above 1000 RPM.

jrichker · Sep 8, 2019

TTSaleen05 said:
Thanks richker, I’ve been scrolling through that thread tryin to a find a fix. The sucky part about it is that I can’t do a cylinder balance test. It barely gets above 1000 RPM.

Try the fuel pressure check with the engine running at 1000 RPM or higher.

Check fuel pressure:
The local auto parts store may rent or loan a fuel pressure test gauge if you don't have one.
Disconnect the vacuum line from the fuel pressure regulator. Check it for evidence of fuel present in the line by removing it and blowing air through it. If you find fuel, the fuel pressure regulator has failed. Reinstall the line; leave the fuel pressure regulator end of the vacuum line disconnected. Then cap or plug the open end of the vacuum line and stow it out of the way.
Connect the fuel pressure test gauge to the Schrader port located just behind the alternator.
Turn the ignition switch on & start the engine. Observe the pressure: you should see 38-41 PSI at idle.
Turn the ignition off; reconnect the vacuum line to the fuel pressure regulator. Then disconnect the fuel pressure test gauge. Watch out for squirting gas when you do this.

Fuel pump pressure test
Disconnect the larger of the two fuel lines up by the Schrader valve. It is the return line and does not have the Schrader valve on it. Find a piece of rubber fuel hose and clamp it on the return line coming from the regulator. Stick a bolt in the other end of the hose and make sure that all your connections are tight and leak proof as possible. When this powers up, you don't want fuel squirting everywhere. Hook up the fuel pressure test gauge. Turn the ignition switch on and watch for leaks. You may want to use a helper inside the car to cut the switch off quickly if you have a leak. To trick the fuel pump into running, find the EEC test connector and jump the connector in the Upper RH corner to ground.

Caution!!! You have blocked the return line for the fuel pump! Pressure will rise very quickly past safe levels with a good pump
If the pressure goes up past 55 PSI, the pump is good and the fuel pressure regulator is bad. If the fuel pressure does not hit 55 PSI or more in a few seconds, the pump is bad or you have electrical problems.

TTSaleen05 · Sep 8, 2019

I had a fuel pressure tester, I took the vacuum line off and hooked the gauge up to the Valve. At idle it read about 36 psi, and I tested it with the key on engine off to see if it would hold pressure. I feel kind of bad because I didn’t test it while applying the throttle.

TTSaleen05 · Sep 8, 2019

I will retest tomorrow morning to see if it checks out

Engine Multiple engine codes

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