Cold Idle Problem

[Stickman]

So, after engine swap, got my ride back.
Upon initial start, after idle comes down to norm (800 - 1000), it won't hold at 800.
Keeps dropping, chokes, tries to increase, revs up to 2000, dies back down, can't hold idle, and stops running. Restarting produces same results.

I have to start, rev it myself to 2000 RPM, let out clutch, then go. It will kill if I accel;erate too hard.

After a few minutes of driving, all is fine, idles 800 at stop lights, etc.

Let car sit a bit and same problem, just not as long to get it running normal.

Thanks for your ideas.

 

[GlowstickNinja]

Are you pulling any codes or is your check engine light on? Sounds like an intake/compression issue. Could be mass air flow sensor, intake, injectors, coils.......

Could try disconnecting the battery cable, pushing on breaks for 15 seconds (to rid machine of power) and reconnect.

Also, is the engine us spec or jdm? if jdm then the ecu may need to be different as well as per they have different cam shafts.

These are all thoughts, someone please correct me if I am wrong.

 

[MazdaSpeeder]

Any info on the engine would help..mileage, history, did you do anything to it before you installed it? Could be that the EGR is really coked up, but the problem sounds more severe than that. It almost sounds like the timing belt could be off a tooth...did you change the belt before installing the engine?

 

[Stickman]

114k miles used motor out of 02 protege.
No codes. Mechanic cleaned Maf.
Replaced valve cover w/ my orig cleaner one.
Also replaced h2o pump and timing belt.

 

[Tiajaunatoad]

I agree with Mazdaspeeder on the timing belt. I've installed them and 1 of the cam gears off 1 tooth and they will do some weird stuff as far as idle and drivability concerns go. Also if the motor has been sitting up for awhile the iac valve could sticking.

 

[Stickman]

Where is iac valve?
If belt off one notch, wouldn't it show same symptoms when it warmed up? How can I check correct timing belt position w/out going to dealer?
Thanks

 

[MazdaSpeeder]

You can pull the IAC and clean it no problem. It's on top of the intake tube, and it comes apart with a few screws. Scrub all the carbon out of there and you should be good, but I still think it's the timing belt. I doubt the IAC would cause something this severe. Tiajaunta is right...one tooth off does funky things.

If the mechanic did the timing belt, take it back and tell him it is off a tooth. He installed it wrong, he should fix it for free.

 

[Stickman]

One would think timing belt would cause it to run improperly all of the time, not just when 1st starting/ not to temp. I'll check w/ mechanic but it would help to let him know how to line up this specific Mazda.
I'll check out the IAC, can always swap w/ old one from other motor.
Computer no longer throws codes, tested by leaving gas cap off, so looks like there are other issues.

Thought this engine swap would be "plug-and-play". Not going as well as I thought.
Anyone w/ ideas please help. Thanks.

 

[MazdaSpeeder]

Is it not an FSDE? The mechanic should know how to line up this specific Mazda. You can find the procedure in the shop manual posted in this section of the forum, but it involves lining up the two cam gears to one another (they have an arrow on each). I've never done it, but from what I understand, it is easy to get them pretty close and be off a tooth.

You say the computer no longer throws codes...could it be throwing codes and the CEL light is out? Does it illuminate when you turn the key on with the engine off?

 

[Stickman]

Yah, CEL light works. Lights when starting. Worked prior to engine swap, back then showing cyl 4 problem, the one w/ the bad lower bearing.

Stopped by mechanic yesterday. He already checked and cleaned MAF, IAC, wiring connections, and timing belt position.

Disconnected coil and ran, which should show immediate CEL. NO CEL's. so can't eval problem by CEL codes.

Help.