Micheal Nadeau
Active Member
Even if the ECU went, you should be able to run it with out the spout and have it idle and rev fine. Is it possible you are 180 degrees out? The back firing through the intake suggests, to me, that its 180 out.
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I had the engine running without the spout connected and it was doing the same thing. It is not 180 out, I lined the timing marks up with cam at 6 o'clock and the crank at 12 o'clock then I installed the distributor with rotor at number 1 position.
Micheal Nadeau
Active Member
Ok, was number 1 on a compression. Stroke? Just installed a cam, head and dizzy in a jeep today. Same problem your having. Acted like it was running on 3 cylinders. Had #1 tdc, cam/crank dot to dot and stabbed the dizzy at #1. Had to pull the dizzy and spin it 180, because I set up on the exhaust stroke and not the compression stroke.
The crank turns twice for every one revolution of the cam, with the timing marks lined up at 6 and 12, it is at the cylinder 1 compression. I believe that mopar is supposed to be at 12 and 12 for cylinder 1 to be on compression. I replaced the timing set in this engine about 2 years ago and put it back together the same way that I did this time and had no problems.
Update: Some of you suggested that I may be 180 out, following this possibility I turned the distributor around and it just popped and would not start. Is there anything else that anyone can think of that may be the cause of the problem that I am having? I performed a smoke test and there were no signs of leakage and once I uncorked the throttle body to put everything back together, all of the smoke billowed out, so I know I do not have any vacuum or intake leaks. The only thing I have not tried is putting the cars original ecu, which I really want to avoid doing at all costs. Thank you for any and all responses.
"When the idle is 1000 rpm, my vacuum is at between 5 and 8 inches of vacuum and the air/fuel ratio is at about 19.8." The 5"-8" of vacuum suggests a vacuum leak.
"I tried everything I could think of and it still runs like crap and pops out of the intake like the timing is off".
"...the air/fuel ratio is at about 19.8. "
The backfire is because you have a lean mixture.
Backfiring out the intake is either a valve stuck open or a lean mixture or spark plug wire(s) connected to the wrong cylinder(s). Check compression on all cylinders and then look for vacuum hoses loose, cracked, or misconnected. Check the line for the vapor recirculation system – it is easy to knock loose and not see it when you connect the air pump plumbing. If the vacuum line for the EGR valve and the air pump are cross connected, some very strange things can happen. Check the mass air flow electrical connection and see that it is tight, the same goes for the fuel injection wiring harness connectors up on top of the manifold near the firewall.
Sticking valves: If a intake valve is bent, has a bad spring or is misadjusted, the engine will sometimes backfire through the intake. Use a vacuum gauge connected to any convenient spot on the intake manifold. Run the engine at 1000 RPM & look for 18-21 inches of vacuum with a steady needle. A problem intake valve will make the vacuum gauge needle sweep 5-10 inches.
Lean fuel mixture breaks out into several sub categories:
A.). Vacuum leaks
B.) Air entering the intake without passing through the MAF on Mass Air cars (89-95 models).
C.) Failure of the MAF, BAP/MAP (Baro or Manifold Air Pressure, same sensor, different name), ACT (air charge temp), or ECT (engine coolant temp). These should set a code in the computer.
D.) O2 sensor problems: one or both O2 sensors with low output or bad O2 sensor heater ground. This should set codes 41/91. The O2 sensor heater ground is an Orange wire in the engine mounted fuel injector harness. Ground it to the back of the head or intake manifold.
E.) Leaking exhaust gases from EGR valve at WOT or EGR opening when it should not be open.
F.) Poor fuel delivery due to bad fuel pump, clogged filter or bad fuel pump wiring. Look for low pressure or fluctuating pressure. Standard injector pressure is 39 PSI at idle, with the vacuum line disconnected from the regulator and capped.
G.) Clogged fuel injectors.- see the cylinder balance test below
H.) Fuel injector wiring problems causing injector not to deliver rated flow (dirty or stuck shut injectors).
I.) Computer problems: (computer problems are not common like sensor problems)
J.). ROM has bad data in fuel or timing table. This should also set a code in the computer.
K.) Failure of one or more of the computer's driver transistors for the fuel injectors. No code set on this one. Use a noid test light to test the injector wiring & injector drivers,
L.) MAF calibration off or mismatched to injectors.
M.) ACT or ECT bad. Sometimes the sensors will be off calibration, but not bad enough to set a code. If they falsely read too high a temp, the engine will back off fuel delivery.
The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8
Vacuum leak due to slipped lower intake manifold gasket...
Ask Nicoleb3x3 about the intake gasket that slipped out of place and caused idle and vacuum leak problems that could not be seen or found by external examination. I don't care what you spray with, you won't find the leak when it is sucking air from the lifter valley. It simply isn't possible to spray anything in there with the lower manifold bolted in place.
I just got finished putting the car's original ecu back in and it runs a little better, do not hear anymore back fire through intake, but still not quite running right. It is still changing idle on its own, but not quite as bad as with the ecu I had in my other car when it was wrecked, only from 1000 to 2000 rpm. I opened up the ecu I had in my wrecked car and found a few burn spots on the circuit board, probably from the tow company leaving the power on.
I am going to do that tomorrow morning. I will let you all know what happens then. Thanks to everyone who has been trying to help me with this issue.
Update: I was messing with the timing and I couldn't quite get it corrected. I removed the cap and inspected the internals and saw that the stator did not quite look right. I disassembled the distributor as much as I could to get a clearer view of the stator, and it looks to me that the contacts are badly burned. I have attached a couple photos of it from each side. It seems to me that this could be a big part of the problem I am having. What do all of you think, should I replace the whole distributor or should I replace the stator assembly?
Attachments
That would not have caused the problem. Electronic components usually fail because they have been subjected to overvoltage or overcurrent or polarity reversal of the power supply..
The exception to this is electrolytic capacitors, which fail with the passage of time. The electrolyte breaks down and the cap shorts and blows the remaining electrolyte out This makes a stain on the PC board and a bulging top or sides of the cap can.
Well, I did not even have that ecu in the 86 for a year, and I bought it brand new from Summit Racing, and it ran fine before I had the accident. Isn't a battery being shorted out through becoming grounded reversing its polarity?
No.
Reversing the polarity occurs then positive output is connected to negative input and negative output is connected to positive input.
That's what happens when you put the battery in backwards. Smoke and sparks and lots of thing that don't work anymore.
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