I'm posting this for a friend.

First the details: 2004 Mazda with the latest flash, new spark plugs, fresh rebuilt engine. Engine rebuild had "just about all the internals replaced". Has over 100,000 miles on the car. Has original coils, fuel pump, catallytic converter, and old starter(replaced but still the '04 kind).

When he got the car back from the mechanic some of the VFAD was not working correctly due to being hooked up wrong. Got the print out from the dealership and hooked everything up the way it should be. Double checked everything with my car.

So here's the problem. No power below 4500RPM. Before the VFAD was hooked up correctly it was really bad, now its only just bad. Its also suffering from very hard starts. Its always been a little hard to start due to the '04 starter on it, but it takes 15-30 seconds of cranking for it to start when cold.

Last detail of the puzzle is it only does this when cold. After the needle has shown it being warm for a few minutes it starts to act better.

I'm sure I missed something so if you need more details ask. Anyone have any idea what might be causing this. He's out of warranty and throwing parts at it blindly is not a choice.

Edit: told me dealership tested coils and said they still worked like new.

 

Cold, slow start...

Easy re-charge or replace the battery. Its 4 yrs old.

Runs odd, re-set the ECU. Also clean the MAF before you do this.

 

Good suggestions. He does have a K&N drop in filter. As the problems started after the rebuild the filter could of gotten re-oiled.

Battery is easy to check. We can swap with mine(when my car gets out of the dealership). My car starts instantly.

Keep the suggestions coming. We'll try to work on it this weekend

 

is it taking longer to warm up?

 

Also, the lack of power may have something to do with the original coils that have 100,000 miles on them.

 

yeah im not convinced the coils are good. they should just be replaced

 

have a scanalyser or the like to look at pending codes?

 

No scanalyzer. Wish I had one, it would come in handy right now. I don't think anyone in Houston that comes out to meets has one either. Only 2 people have accessports!

I'm worried about the coils as well. I have a set of BHR coils just sitting on my table at home. My car is in the shop for transmission work so it might be another week or 2 before I install them.


Edit: It seems to run alot better after the temp gauge is on "normal" for a few minutes. Of course the temp gauge is a dummy gauge...

 

what i mean is - does it seem to to be getting to operating temp in the same time as it did previously. could be a t-stat issue and/or a temp sensor issue. if it thinks the car is really cold it could be limiting it to very rich open loop maps.


ohh had a thought- O2 sensors? if they arent reading the cat temp correctly then it will stay in open loop longer.

and remember the temp gauge is not a dummy- it operates up to normal temp and then has a "window" where it doesnt move and then above like 220 it spikes up again.

 

wow keep us posted i'm curious to see whats wrong with the car!

 

Thanks Zoom, really good ideas that could easily be solved with an accessport or scanalyzer. He doesn't have any CEL's and he took it to the dealership and they did run basic diagnostics. So no CEL's or pending codes. At least none that the dealership mentioned.

 

Replace the coils.

 

Plan of attack:

Replace coils

check volts on battery(I'll tell him to replace battery, its 4 years old and needs replacement as part of preventative maintanence)

Clean MAF sensor

Reset ECU

 

Thanks for the head-start on the trouble shooting, HeavyMetal.


The car we are discussing is mine. Allow me to fill in some of the details.



I got the engine rebuilt in late November. Right away there was a noticeable lack of power in the low end... a VERY VERY VERY noticeable lack of power. However, above 4500 RPMs, the engine felt brand new. I put some miles on it, and things got better, but not perfect. The car still had trouble starting, still felt weak as hell below 4000RPMs, but actually felt faster in the high end.

Then, about 3 weeks ago, I got a very random, very VIOLENT misfire. The car shook back and forth, the differential clanked, and the engine made some very unhealthy sounds. Not suprizingly, after I smashed the clutch in and let the car settle, I had a check engine light. So I took it to the dealer.

They noticed right away that all of the hoses and whatnot that control the VFAD were gone; completely removed. The only code thrown was that of a misfire. I had them reconnect the VFAD, as well as check anything else that could be to blame for power loss. They found nothing.

That brings us to present day. When I start the car after it's been off for several hours, it still takes 5-10 seconds to start. With the clutch in, it sounds fine, revs fine, and seems healthy. As soon as I start to come off the clutch, though, the revs drop and the car sputters like I ran out of gas or something. I mean, the engine can barely pull the weight of the car out of its parking spot. If I'm at 3000 RPMs in 1st gear and floor it, it takes about 10 seconds to reach 3500 RPMs, violently shaking and jerking back and forth the whole time. I never get a CEL.

The temperature needle climbs up at the same pace it always used to. As the needle raises, the engine becomes more predictable. After about 10 minutes of driving, when the needle hits the midpoint of the guage, the car runs better than ever. It's got a *teeeny* absence of power until about 3500RPMs, at which point you can just feel the power swell all the way up to 9500. And it's WAAAY more than stock power - Head to head against HeavyMetal, I'll never stop pulling away.

Also, once it's warmed up, starts are far less dramatic.

WTF is causing this?





ALSO:
ECU was reset today at dealer. Did nothing.
Battery is only a year old. Dealership tested voltage and it's fine.
Spark plugs were replaced during rebuild.
Dealer tested coils and said they were all to spec.

 

Coils need to be replaced every 15,000 - 25,000 miles, I think(someone back me up here). Although they may be "up to spec" it doesnt hurt to change them. If they are the originals like stated above, I would change them asap. You are certainly experiencing a strange issue. There is going to be a long list of things to check. I would refer to the Service Manual or Workshop Manual, whatever it is called. It is available on the forums somewhere, pm me if you need it and I can try to email it to you. Was the Rebuild done by a Dealer? If so, keep bringing it back to the dealer for warranty work. Don't let them drive your car until the engine is cold so they can experience the issue, as you said it is more dramatic cold. Clean the throttle body while you do the MAF sensor, cant hurt

Fluids?? I may be completly wrong, but it may be possible the wrong oil was used. If it is too thick an oil, it will not circulate properly, but when it warms up, it gets thinner causing the symptoms to slightly fade.

I'm probablly wrong, but I may spark something lol.

 

I have the BHR kit sitting on my table. We can install the new coils and by the time we get finished the car should be cold.

Mazdamaniac has reported that you can't really test the coils. Mostly because even if they test out ok, even if they are brand new out of the box, swapping them out with different coils give better results.

If the BHR coils don't solve the problem, we swap them back out and that's that. My car is going to be in the shop until next week at the earliest so if we don't have time to pull the coils back out we can do it another time.


We can also clean the MAF while we are at it, but it doesn't seem like that would be the problem. I just want to eliminate possibilities.

 

Do you know what kind of oil was used? Was the rebuild performed by Mazda Dealer?

 

No, but the oil shouldn't matter that much. I've run 20w50 in mine during summer for autocross and didn't have any problems.

I doubt oil would cause this much of a problem.

 

20w50 in the SUMMER for AUTOCROSS. How about 20w50 in the WINTER for normal driving? Don't know how well that will work. I could be wrong though. Im not saying it is causing every problem, but I cant imagine it helping in the winter.

 

ok read 1/2my's post- cat fried. drop it and look

 

Isnt there an easy way to check that? Like drive around for awhile then when you get home, look under your car for a mystifying red glow?

 

Best and only way to check the cat seems to physically inspect it from the front.

Usually that shows loss of power in the upper RPM's

 

My other thought is if the VFAD was not hooked up properly do you have one of your shutter valves stuck open causing low end power loss? If the SSV is open at idle that will screw up your low end power as well. You should have a code for this correct?

 

No CELs.

Hopefully the VFAD is intake system is hooked up correctly. He still has stock intake.

 

I meant to say if the VFAD was screwed up the rebuilder could have screwed up hooking up the SSV as well. You may want to verify it is working properly.