Recently bought this car. The previous owner said that the coil pack was changed. That is all I have to go by...

When I drag race my buddy in his 94 we are dead even, he may pull on my a bit. I also have a 91 with 19x,xxx miles that feels faster.

What things can I check? I don't get any additional pull in lower or higher RPM's. Is my VVT functioning? How can I tell?

Should I replace the coil packs again? Change all wires and plugs again?

I'll pull the plugs and do a compression test. Anyone know what number I am looking for?

Wish I could give more info... Thanks for any help.

 

The car has about 140,000 miles on it.

 

5 or 6 speed; what wheel/tire size are you running?

I'd like to see about 170lbs of compression.

 

6 speed, 15 stock wheels from a 2000. 195s. I'll test compression this afternoon.

 

PSI from front to back
152, 153, 153, 158

Is this a problem? I'm also getting a code from the cat.

 

Definitely low for a standard engine, but not on the death bed yet.

 

I just re-tested. This time at WOT with all the plugs out. 7 cranks on a weak battery.

Front to back 168, 171, 167, 166

Guessing this is ok?

I'll run some seafoam through and see if that helps.

My code is the cat converter. Do these things go bad? What is a sign if it has gone south?

Ignition coil packs. It has one new one and one older one. Can I test these?

 

Yes, cats can get plugged. That will definitely hurt power. An exhaust shop will be able to test for a plugged cat by monitoring exhaust back-pressure.

Your engine compression looks good.

 

How does one measure back pressure? I have an OBD-II thing, is this a reading I can get from that?

 

Getting codes P0103 and P2004.

 

What an exhaust shop usually does is find a place where they can put a pressure gauge on the exhaust upstream of the cat. They then monitor backpressure with the engine running. I've seen them use the O2 bung for this. Sometimes they drill a small hole for the test.

This is not a parameter that appears in OBD-II.

 

Google is your friend, but I happen to know the first code.

po103 is an unexpectedly high reading from your MAF (voltage of the input signal is above max range).

P2004 has to do with the VTCS being stuck open. Check out this service bulletin from Mazda about it.

 

Great link. I cleared the codes and the P2004 keeps coming back. I just started getting this code after I sprayed deep creep into the motor today. Wonder if the deep creep stuff was too stout.

Just got my hands on a high flow cat. Taking it to be installed this week.


FWIW: I've driven Hondas and such with the VTEC and this VVT motor doesn't feel at all like that. Matter of fact I don't hit any type of "Power Band" (Old 2 stroke dirt bike term)... Feels pretty linear.


Shouldn't I feel something extra as I climb in RPM's?

 

No, it doesn't ramp suddenly like vtec.

 

On some vehicles, after sitting overnight and being started, the MIL comes on and DTC P2004 sets into PCM memory. This occurs because vacuum (momentarily) does not flow into the Variable Tumble Control System (VTCS) shutter valve actuator. The contact surface between the valve and the valve body inside the check valve is smooth, causing the valve to momentarily stick before more vacuum applies, opening the valve.


Is the VTCS something that could get in the way of this motor making power?

 

Comparing VVT to VTEC...lol. Not nearly on the same level hahaha. Look up both acronyms and use deductive reasoning to figure it out.

If the VVT is not working (rarity), it would result in less peak HP from Mazda rated it at. Also, a timing belt off a tooth could do it. If the VTCS is broken/stuck, it would definitely cause a loss of power.

This is the VTCS system, clearly if the actuator was not working or the butterflies were sticking closed....well...you can guess..

 

Have to admit that I am not fully aware of how the VVT motor functions. Working on it. I'm a Corvette guy. GM has had the same push rod design for a while. I originally bought this miata for my GF to race while I raced my C5. But then I started to like running the Miata. Now I'm hooked. I can field a Miata on street tires and no prep and still have a good time. The vette can be a handful and without blowing $1750 on slicks twice a year it's unusable.

I need to get this Miata going right. I already have a good suspension and a roll bar. If I get all the normal stuff sorted out I may be looking at a flying Miata turbo kit soon.


Is there a way that I can check and see if the VVT part is functioning?

And this VTSC actuator code, the message states it needs a new adapter. Is this a factory recall or something I need to go buy?


Basically I am stating that yes, I am a newbie. And I appreciate any help you guys are offering to help me get this car in shape.

 

Hey Mike (Doppleganger) is there a vacuum tube that goes to the bottom of your intake? Told that this may be the cause of the 2004 code.

 

Found a vacuum hose off the car. It runs a lot better now. But still not up to par with where I think it should be. I'm going to have a high flow cat installed and see if that helps.

 

It's all good
If the VVT is out of whack, it should throw a code. I have not seen it fail for the most part, other than when people pull it apart by accident. I'd also throw a timing light on it just to make sure the timing is correct. It would almost seem more likely that the timing would be off or something of that nature than the converter being clogged. It would help you greatly if you could throw a WB02 on there and watch your AFRs.

If you're going to do any playing with the exhaust, you might as well just get a newer, better system. I'd highly recommend looking at Enthuza exhausts.

Funny what a little vacuum leak can do.