ROUGH IDLE

Got some of the electric gremlins chased down. Next- Idles rough up to 2500 rpm then runs fine. Compression is 130-135 cold,throttle closed. Plugs are weird. #1 and 4 are grey- tan, #2 and 3 are sooty black.

Any thoughts?

Bob

Got some of the electric gremlins chased down. Next- Idles rough up to 2500 rpm then runs fine. Compression is 130-135 cold,throttle closed. Plugs are weird. #1 and 4 are grey- tan, #2 and 3 are sooty black.

Any thoughts?

Bob

Rough idle could be a dozen things, but lets start with two different color plug wires and look at the obvious first.

Two different types of plug wires that show to the world make me wonder what things look like under the rotor cap, what about the electrode end of the plugs? Take a look and see what you for plugs, wires, rotor and cap.

I am referring to the electrode end of the plugs, not the wires.

Wire look good and measure around 7.5 k ohms.

Cap and rotor look good.

Bob

Are the plugs all the same heat range? Same manufacturer and length from outside thread end (includes ALL of the thread in measurement) to tip of electrode? Cap could have hairline cracks that only show up at full engine compartment heat. After that I am thinking all that is left would be a valve problem, injector problem (harness?) or a head/headgasket problem.

All plugs identical.

Compression check should show head gasket/valve/rings problem.

Would an injector problem show rich on 2 plugs and lean/good on other 2?

Since this car is new to me I am going to replace plugs, wires, cap and rotor so I am starting with known good ignition system.

Bob

Compression testing will show compression leaks; leaks that seal on compression just plain suck.

You could have bad injectors and the control module could be squirting extra motion lotion through good injectors as it tries to balance the books with a to lean report from the O2 sensor. Or HAL could be fibbing to the controller.

Because you seldom know when the last time normal maintenance was normal, it's always good to do the normal maintenance when you get a new used unit,

Before you get too carried away with chasing after all things imaginable ask your car what it knows. Check your engine codes by turning your key on off on off and back to on and wait for the code to start flashing on your check engine light. All codes flash in two number groups with a couple of seconds pause time between the first number and the second. When you're engine light flashes five times and then flashes five times again, it's done talking. There are 101 things these old systems won't tell you that new cars do, but what it can tell you is worth knowing.

As far as the codes go I have an OTC Monitor 2000 which reads codes as well as sensor inputs and can output certain control functions. Picked it up at a swap meet 20 years ago for my IROC Z. I will check the codes after I replace the ignition components and report back.

Bob

As far as the codes go I have an OTC Monitor 2000 which reads codes as well as sensor inputs and can output certain control functions. Picked it up at a swap meet 20 years ago for my IROC Z. I will check the codes after I replace the ignition components and report back.

Bob

Never used the OTC, I hear it's a good unit, but it might not work with your TC. Did some trouble shooting on a TC a couple of weeks ago and my tester wouldn't work with that car, after I made sure my tool was good I was considering a possible engine control or cable problem until Hemi told me that some TC's won't talk to these.

New plugs, cap, rotor and wires. No change- still missing. No fault codes either. Tried bringing up the rpm under load(in gear. brakes on) and the problem seems worse even at at higher rpm than idle.

Where are the timing marks to set the timing?

Bob

New plugs, cap, rotor and wires. No change- still missing. No fault codes either. Tried bringing up the rpm under load(in gear. brakes on) and the problem seems worse even at at higher rpm than idle.

Where are the timing marks to set the timing?

Bob

Love this one if you have the SOHC that is the 8 valve 4 cyl, the timing window is below the air cleaner and you need to pull the air box to see it. If you have an adjustable timing light there is a hole to the front of the tranny bell that you can view the mark through, but greasy dirt might mean that you still need to pull the air box to clean the mark so you can see it.

Quickest way to find the mark is pull the dist cap, get the rotor pointed to #1 plug and dab some white paint in the dip.

Set your timing with engine warm, pull the temp sensor plug and set to 12 (though you could set to 10 and if everything works as it should you might like the way the motor runs here better than you do at factory spec 12). Excessive engine surging while setting timing means you have an un coded problem and you could leave timing at 10 and wait for the car to strand you so you can find out what it is, or you could save some trouble time and replace both the IAC and MAP now.

2 new bits of info. While setting timing I noticed a mechanical clicking like the A/C clutch. (It was not A/C clutch)The sound was more frequent when timing was retarded.

Checked fuel pressure- 52 psi. and dropped to 0 in about 15 seconds when engine shutdown. Is this normal to bleed down so quickly?

Bob

2 new bits of info. While setting timing I noticed a mechanical clicking like the A/C clutch. (It was not A/C clutch)The sound was more frequent when timing was retarded.

Checked fuel pressure- 52 psi. and dropped to 0 in about 15 seconds when engine shutdown. Is this normal to bleed down so quickly?

Bob

Bleed down with time is normal but 15 seconds is pretty darn quick.

You sound like a man with tools and mechanical know how so I can point you in this direction, but you will have to figure out what you can do with what you have.

Bleed down question first; if you have nothing at all to test bleed down you can plug flex fuel line feed to engine, turn key on and let fuel pump run for a few seconds before turning key off, look for any gas leak between tank and plug, then cover plugged end best you can to prevent fuel from spraying everywhere and remove plug to test quality of fuel pump. This should spray some gas so don't do over warm engine and definitely not while smoking. Any pressure in line means looking to fuel pressure regulator and or leaking injectors which from the plug end description could be you problem.

Clicking or ticking? not hearing with your ears I have to ask were you able to identify the sound to general location? Snapping will also sound like ticking and snapping from electrical short can be found in a darkened work space. For this you can retard in the dark and look for spark. I doubt that with new plugs and wires that this will be the cause, but it doesn't hurt to look.

Clicking sound seems to be coming from intake manifold. I thought it might be backfiring into intake.

I have been twisting wrenches on everything from an A/FD to Ford tractors for the past 50 years-always as a hobby.

Bob

Backfire into the manifold does make kind of a bad bearing sound where there is no bearing. You wouldn't believe the sounds this motor makes if you pinch off main vacuum and fudge the timing to make the motor run.

Made a mistake- clicking increases when I advance dist, not retard.

Ran the engine last night after dark and no arcs or sparks. I did have some smoke from the back of the pump motor below the master cylinder. There are 2 wires going into the motor with a thin metal strip in between them where the smoke was coming from.

How difficult would it be to swap injectors around to see if the soot/rich problem is caused by the injectors? The Monitor box had a "rich" light on while I had it connected and the engine was running.

Bob

Swapping wouldn't be any harder than replacing all 4 injectors, these things are a few years old, plug and play swapping could leave you with fuel leaks from old O rings and rockauto sells standard motor parts injectors $22 ea. For less than $100 parts and shipping is it worth doing the job twice, personal choice.

Smoke from the brake pump would be my priority, I wrote a post about a month ago comparing our pump wiring to a toaster cord and smoke is a very bad sign.

Smoke from the brake pump would be my priority, I wrote a post about a month ago comparing our pump wiring to a toaster cord and smoke is a very bad sign.

Searched for your post- no luck.The search function on this BB is less than stellar.

Bob

Searched for your post- no luck.The search function on this BB is less than stellar.

Bob

Took me a while to find it myself, posting was started by argyle on Sept 16 and my toaster description is at the bottom this should help http://forums.aaca.org/f144/89-tc-2-2-auto-abs-359033.html