StarionX

If I start the car when engine is cold, warm it up and drive around for 20 minutes, everything works fine (except I still have 3800 hesitation). I shut the engine down, then let it sit for 20 minutes. Then I start it up, the car will drive like it's not getting enough spark (slow accelaration, very hard to get to max boost).
I've been told that the coils could be going bad, as they still work ok while engine is cold. Here is the bizarre part. If I start driving the car when engine is cold, I can drive around for hours, and it drives just fine. I only seem to have problems after restarting the car (which by the way, I need to use the fuel cut-off switch to start). If I can drive for an hour with no problems, it would seem to me that 'heat' should not really be an issue. For various reasons, I've replaced fuel filter, air filter, oil and oil filter, spark plugs and ALL vacuum hoses. The only 'mantenance' thing I haven't replaced are the ignition wires.
Does the problem I have make any sense at all? Any ideas would be welcome.

HAILERS

From the description it sounds like the car is onl y running on the trail coils assy when hot. Next time it does that, pull out the timing light and see if the lead wires are sparking.

Here's the real deal. On some, not ALL RX'S, there is a grounding issue with the ECU. I found after a lot of troubleshooting a year plus ago, that I had to add an extra ground to the ground wires at the ECU. In particular, the ground wires at the small plug. This is a FIX for hesitation.

Just this last week I realized I had 3800 hesitation. I looked at my ECU. I had been playing with the ECU, and when reinstalling it, I had left off the ground ring that I had previously added a year or more ago. So, to prove this was the problem I went for a ride. It hesitated. I pulled over and attached the grounding ring and torqued it down. Drove. No hesitation.

I mention the grounding fix just for the hesitation problem, NOT the car pulls like a slug problem when hot problem.

I have three of these cars. Only one car has to have the extra grounds. The other cars are just fine. And yes, the ECU ground lug on the top of the engine is there and grounded just fine thank you. Here's the deal. The ground wires at the ECU go to a place in the harness where three or four more wires are soldered to these ground wires. I suspect cold solder joints at this place, but it means the harness would have to be taken apart, as in unwrap the covering and try to find the solder joints.

StarionX

Assuming I get little/no spark, what does that mean? Coil replacement?

HAILERS

You could go to the wreck yard and buy a lead assy for twenty to twenty five bucks.

No spark? I'd look for 12v on the black/yellow wire at the little white plug connctor at the lead coil assy.

There is a checkout of the lead coil *** in the fsm online at http://www.iluvmyrx7.com

StarionX

Thanks Hailers.
The sad thing is I had both coils replaced by a Mazda Dealer, 5 months ago. They told me they were going to put in aftermarket, as it would be cheaper. Still cost me CA$600 for both. What they DIDN'T tell me (and I only found out when I checked the bill after I got home), was that they were used.

dr0x

600$ for used coils? OUCH! Next time find a parts car, or go to a junk yard... These dont have a constant problem w/ failing. I dont think a used one will hurt anything, except for your wallet in your case

HAILERS

That is sad. Ones in the wreck yard can be had for twenty to twenty five and are usually good. I don't read about many if any lead coil assy going bad. I suppose they do though.

One thing I've learned in the last year or so, is that the coil assy MUST have a good bond with the chassis or it WILLNOT work at all. Probably not your problem, but you might make sure the three nuts for the assy are tightened down with no rust under them. Sad about the six hundred.

StarionX

Yeah, it still hurts when I sit down.
And just another reason to hate Dealers!