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I have a problem with my car... If you know anything about cars please help!!
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24 / F / Nebraska
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Posted 4/14/08 , edited 4/14/08

lasthope05 wrote:

The car is cycling in open loop mode most of the time. I have my LM-1 wideband simulating both a narrow and wideband. Its an ob1 car so the only codes it throws is the important ones. The car could possibly have a leak though. That could explain some of the issues.


What I'm not too entirely sure about is how a vacuum leak affects the transmission in a manual transmission.
Since shift points are based more off driver demand then PCM data of engine load.
Correct me if I'm wrong though...since that was just pure speculation.
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Posted 4/14/08
Well.. the car is a manual transmission. Im not sure where you getting at with that. Im not having transmission problems or any sort. Haha..Well I guess I'll let the cat out of the bag. There is nothing wrong with my car. I was just trying to liven up the car forums as I've seen a decline in participation from a couple fellow members.

But I made this thread sorta as a game for those who want to participate to demonstrate their diagnostic capabilities. Can anybody still figure out the problem though?
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24 / F / Nebraska
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Posted 4/14/08
Aha nice.
But one of your "complaints" was that there was hard shifting?
Or I must've misread that. Aha.
And yeah, this sparked my interest.
When I saw the title of the thread, it was like...finally...yes, not another "best" thread.
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24 / F / Nebraska
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Posted 4/14/08
Aha but I give up, what is the problem?
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Posted 4/14/08
Actually this was a problem that I really did have but I figured it out in a matter of minutes. There wasnt hard shifting but when I was shifting "aggressively" the car would bog for a bit and almost die out.

Yea I read somewhere someone was tired of the same post and I thought the same. It would be nice I after someone figures out this little problem someone else can present us with another so maybe I can participate in diagnosis too.
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24 / F / Nebraska
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Posted 4/14/08
Aha I have one.
My 97 Mazda 626 has an idle surging problem.
No codes, no CEL, nothing.
Also, its a 4 cylinder and cylinders 1 and 3 have a compression ratio of 80 psi and 2 and 4 have 150 psi.
Aha I've already diagnosed this and corrected the problem.
Let the games begin, hah.
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Posted 4/14/08

pookie052606 wrote:

Aha but I give up, what is the problem?


Haha.. No patience to figure out the problem?

Well it was due to a multitude of problems. Since im turbo and am a maf based drawthrew setup and air that enters threw the maf at is already accounted for so the ecu know how much fuel to inject. We problem was I had a massive boost leak post maf. So the air that the ecu thought it was see wasnt there but still compensated for it by adding more fuel. That coupled with that my bov is also vented so i was loosing more air flow. That accounted for the the rich issue and some of the bogging. The other part of the bogging was due to my knock sensor staring to go bad. It would detect 43counts of knock every now and then and pull my timing all the way back.
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Posted 4/14/08
running rich and bogging between shifts leads me to believe that it is a leak somewhere. check all of your fmic hose clamps, check vaccum hose for leaks, if you have a turbo inlet hose check that for leaks/tears as well, and the most likely- check your bov for leaks.
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Posted 4/14/08

lasthope05 wrote:


pookie052606 wrote:

Aha but I give up, what is the problem?


Haha.. No patience to figure out the problem?

Well it was due to a multitude of problems. Since im turbo and am a maf based drawthrew setup and air that enters threw the maf at is already accounted for so the ecu know how much fuel to inject. We problem was I had a massive boost leak post maf. So the air that the ecu thought it was see wasnt there but still compensated for it by adding more fuel. That coupled with that my bov is also vented so i was loosing more air flow. That accounted for the the rich issue and some of the bogging. The other part of the bogging was due to my knock sensor staring to go bad. It would detect 43counts of knock every now and then and pull my timing all the way back.


AH! Knock sensor...the timing problem threw me for a huge loop.
I speculated that it was a MAF fault, but ruled it out because I thought it would throw a code...(not too familiar with OBD1 stuff).
Aha man..good one.
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Posted 4/14/08

pookie052606 wrote:

Aha I have one.
My 97 Mazda 626 has an idle surging problem.
No codes, no CEL, nothing.
Also, its a 4 cylinder and cylinders 1 and 3 have a compression ratio of 80 psi and 2 and 4 have 150 psi.
Aha I've already diagnosed this and corrected the problem.
Let the games begin, hah.


Hmm.. idle surging problem?. Im thinking either faulty ISC motor or FIAV. I really have to be there and test them out. And low compression in cylinders 1 and 3. Have you performed a leak down test? what did the results say on those two cylinders?

A few reasons to low compression. Valve seats are worn/vavles are cracked. Blown headgasket would account for another and last but not least the piston rings.

So I would need the info on if the ISC or FIAV both tested out ok and the results of the leakdown test.
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28 / M / (In) your Mitsubi...
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Posted 4/15/08
Hmmm, I'm not sure if you've come to a conclusion yet, but it sounds like that you coudl be having some fuel issues. Do you have a good enough fuel pump to top those injectors? Also, how big is your exhaust? By what you have - it sounds like you're pushing roughtly over 500 hp? In any case - make sure you don't have any exhaust leaks too =x
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Posted 4/15/08
I had the crazyiest idle surging problem a while back. I checked everything, vaccum leaks, stuck IAC, faulty maf, intake leak, but it ended up being that the spring for the cruise control broke causing the cable to pull the slightest bit opening the throttle. Sometimes it's the simplest things that take a bit to find.
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24 / F / Nebraska
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Posted 4/15/08 , edited 4/15/08

lasthope05 wrote:


pookie052606 wrote:

Aha I have one.
My 97 Mazda 626 has an idle surging problem.
No codes, no CEL, nothing.
Also, its a 4 cylinder and cylinders 1 and 3 have a compression ratio of 80 psi and 2 and 4 have 150 psi.
Aha I've already diagnosed this and corrected the problem.
Let the games begin, hah.


Hmm.. idle surging problem?. Im thinking either faulty ISC motor or FIAV. I really have to be there and test them out. And low compression in cylinders 1 and 3. Have you performed a leak down test? what did the results say on those two cylinders?

A few reasons to low compression. Valve seats are worn/vavles are cracked. Blown headgasket would account for another and last but not least the piston rings.

So I would need the info on if the ISC or FIAV both tested out ok and the results of the leakdown test.


The low compression was a blown headgasket, aha you're right.

But the idling problem was a whole different one in itself.
The ISC and everything checked out OK.
Another hint:
It was running pretty lean.
Fuel pressure was all within spec.
Fuel filter had been replaced in a tune-up prior.
Cleaned fuel injectors too.

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Posted 4/15/08 , edited 4/15/08

lasthope05 wrote:

So heres the problem. The car has a 60-1, 28psi, large fmic, 960cc, bosch 044, 272s, tial bov and a full tuning device.. Now the problem with my car is its running extremely rich. Boost response is crappy and the car feels sluggish. In between a hard shift or medium the car bogs down and almost stalls it self out. The motor was dropped in a few days go. Just so you guys know. Timing is also low, In the lower to mid teens, dont know why.. Can anybody figure out the problem???


try adjusting your A/F mixture dude....but im not so sure...usually, if a engine is running extremely rich, that means that the A/F mix is unbalanced....too much fuel to air ratio. correct me if im wrong, though.. or your using low octane fuel.....what's you're car's minimum fuel octane?
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24 / F / Nebraska
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Posted 4/15/08

penguinwithm4a1 wrote:


lasthope05 wrote:

So heres the problem. The car has a 60-1, 28psi, large fmic, 960cc, bosch 044, 272s, tial bov and a full tuning device.. Now the problem with my car is its running extremely rich. Boost response is crappy and the car feels sluggish. In between a hard shift or medium the car bogs down and almost stalls it self out. The motor was dropped in a few days go. Just so you guys know. Timing is also low, In the lower to mid teens, dont know why.. Can anybody figure out the problem???


try adjusting your A/F mixture dude....but im not so sure...usually, if a engine is running extremely rich, that means that the A/F mix is unbalanced....too much fuel to air ratio. correct me if im wrong, though.. or your using low octane fuel.....what's you're car's minimum fuel octane?


Low octane fuel would cause engine knock.
As for the A/F mixture, the injectors are pulse-width modulated by the PCM.
Rich conditions are also caused by engine load...either sensed by the MAP sensor, TPS sensor or O2 sensor.
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