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Hopefully someone can help. It won't rev past 2K when driving, and not past 4k in nuetral. I just installed a Cardone reman. distributor from Advance auto parts, and it did NOT help. Now I don't really know what to try next. And I did the HEI module mod to my old distributor before replacing it, and that didn't help. New plugs, wires and disty cap/rotor were changed recently, they still look new on the outside and the disty cap looks fine on the inside, so I can't imagine any of those being the problem.

My one friend said it had a weak spark when we looked at a spark plug attached to one of the spark plug wires, that was before the new distributor with new coil. So since the new parts didn't change anything, maybe the spark is fine, not weak, I don't know for sure.

The engine revs normally and sounds normal when reved up to about 3k in nuetral, but anything over that or a quick full throttle and the engine does not want to rev, you can hear the intake get loud but it doesn't rev. It doesn't miss or hesitate. If I try to drive it, it won't rev past about 2k, the car just won't go. I have a fuel pressure guage that shows normal or good fuel pressure.

Please help, any suggestions? Thanks!

Could the timing be way off causing this problem with the engine not reving up? It's almost like it hits a rev limiter and doesn't want to rev any higher, it sort of bogs at 4k when I slowly rev it up, and when it hits 4k the revs drop about 500. It's worse if I rev it quickly, it won't rev as high if I try to rev it quickly like when going full throttle. It acts normal if you rev it normally up to about 3k.

Please help! thanks.
 

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Thanks for the reply. The fuel pressure guage shows the fuel pressure to be good, it rises when it revs, and it holds pressure when the car is turned off. So I'm thinking fuel is not a problem unless the ECU is messed up or the mass air flow sensor is not working correctly so the fuel injectors could not be putting out enough fuel to keep the motor reving.

Does anyone else think the mass air flow senser could be the problem or somehow a bad ecu? Thanks.
 

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revs

its a VAF. anyhoo, i know u looked but check all your plug wires. on my escort i had one that was grounding out on my radiator and it wud idle fine too but would not go over 3k. the wire or wires cud have pulld off the plug or out of the connector inside the wire.
 

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of all the s-10's i've ever seen, yours is the nicest
 

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Discussion Starter #9
Plug wires and caps look normal. I pulled a spark plug and it is very dry and the tips are a light grey color, and black residue elsewhere. I think that means it is running lean. The fuel pressure is 37 at idle and it goes up to 44 when I rev it (as much as it will rev).
 

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I think it sounds like a bad ecu, but I dont know for sure. It could also be possible that your timing belt has slipped a few teeth. You may have a fuel volume problem not a fuel pressure problem. A gauge wont tell you volume, you need to unhook a fuel line and see how much fuel you get in 60 seconds while turning the motor over. I would unplug your distributor when you do this.
 

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Your catalytic converter could be plugged. I had a very similar problem on my old '87 thunderbird. I removed the cat and it ran perfectly.
 

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Discussion Starter #12
Thanks for your reply. It starts good and runs normal at low rpms so I have always thought the timing should be okay, but you could be right.

The car has been slower than it should be for about a year or two. Then all of a sudden this problem happened out of nowhere, where it won't rev up high. Just before this problem, it seemed like the car would run out of power and not rev all the way to redline, it had decent normal low end power but no top end. It ran like 18 or 19 seconds in the 1/4 mile, so slow! It acts the same way now except it won't rev nearly as high. So I'm assuming it is all related.

A new fuel filter was put on when I did the tune up (plugs, wires, cap/rotor) trying to get my car to run better back when it ran slow before this problem where it doesn't rev up much. I guess I could check the fuel coming out of the fuel filter.


I think it sounds like a bad ecu, but I dont know for sure. It could also be possible that your timing belt has slipped a few teeth. You may have a fuel volume problem not a fuel pressure problem. A gauge wont tell you volume, you need to unhook a fuel line and see how much fuel you get in 60 seconds while turning the motor over. I would unplug your distributor when you do this.
 

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Discussion Starter #13
Your catalytic converter could be plugged. I had a very similar problem on my old '87 thunderbird. I removed the cat and it ran perfectly.
I have thought about that too. I put on a catco converter a few years ago so I assumed that wouldn't be clogged, but maybe I should check. But the engine just bogs when it hits 4k when revved very slowly, so I can't imagine anything making it do that other than the ecu. The faster I rev it, the worse it is. So that makes me think maybe it is the VAF not sending the right readings to the ecu so the ecu is not sending enough fuel through the injectors to keep a good air fuel ratio to keep the revs going. Any of this sound right to you? Thanks again all.
 

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white means its running lean, light grey is what u want to c. if u wud have had wet plugs u wud be running rich. if u do the fuel volume test, u should get 16 oz in 30 seconds. to test the VAF, unplug it once and so how the car runs. if it runs better u hav a bad VAF, worse the problem is something else.
 

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I would think if it was the vaf you would throw a code. So im thinking its not that. unless you are throwing a code??? If it was the ecu i would think it would run like crap or at all but i never messed with any car that had a bad computer so i could be wrong. For any thing that deals with a sencor o2 vaf throttle all should throw a code.
 

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Discussion Starter #17
There was no CEL codes. I think maybe the VAF does not give the correct reading when it is opened past a certain point, which could explain normal operation until I rev it quickly. Has that ever happened with other VAF's?
 

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Are you sure you have no air leaks after the VAF? No vacuum or PCV lines disconnected?

Is it possible that your spark plug wires are in the wrong order? It would start and idle, but you'd have 2 (or more) cylinders not providing power.

Last but not least an exhaust restriction is also very possible.
 

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Discussion Starter #20
Are you sure you have no air leaks after the VAF? No vacuum or PCV lines disconnected?

Is it possible that your spark plug wires are in the wrong order? It would start and idle, but you'd have 2 (or more) cylinders not providing power.

Last but not least an exhaust restriction is also very possible.
Yes there should be no air leaks, I will check again though. The plug wires are good, and in the correct order. I haven't touched those since they were replaced the car didn't have this major problem after I installed them.

It runs and revs normal until it hits 4k rpms if revving up slowly, it bogs down at that point, also it bogs at about 2k if I try to rev it very quickly, and it won't rev past 2k when I try to drive it. It revs and sounds normal if slowly revved up just alittle. The intake gets loud like it's getting all the air it should but not revving, like it isn't getting enough fuel to keep it revving. That's why I think the ecu could be bad, not keeping the injectors open to supply fuel. Or the VAF not sending the correct readings back to the ecu.
 
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