Huge loss of power.
 

Hi Guys,

As some of you know I am running a HKS T04Z and I was pushing 430 whp.
Recently after a track day the car feels like it has lost about 150 whp.

The turbo still boosts the same (1.1 bar) and we tested for leaks and there is nothing. I did notice boost is coming in about 1000 to 1500 rpm later than it use to. We also ran a compressor up the I/C tubing at 1.5 bar and the air is reaching the motor just fine. I run an AFR of 10.2 on boost.

Could the turbo be on its way out, or do you think the plugs could be poked ??(Not sure if plugs can have such a big effect) I have never had any problems with the car so I dont know where to start.

Any suggestions would be appreciated.

Thanks,
BR

have you done a compression test on the motor?

10.2 afr's is a bit rich. Is it running clean? I mean is it smooth going thru the power band? Hate to even say it but my last motor ran fine but just a loss of power and it ended up being a chip seal = low compresion!

I think the compression test is the way to go then by the sound of things.

Sk8World, tell me more about the chip seal that went. Also what an easy way to test the compression without special mazda compression tester and what are the correct readings?

Thanks guys

does it sound like a tractor on idle eg is it idling fine?
Do you have a boost gauge ? if you do then check on idle if the needle "ticking" in the vacuum area, if it is then it sounds like you have chipped a seal

No motor sounds as sweet and smooth as ever. Boost needle is stable on vacuum as well.

Huge loss of power.
 

questions were you running race gas , premix and what kind of spark plugs were you running .

also check the bolts on the back of the compressor housing. Ive lost em before and had the same effect.

also check the bolts on the back of the compressor housing. Ive lost em before and had the same effect.

I use only race gas and I run HKS 10.5 PLugs all round.

Could very well be the bolts, I noticed a loose bolt on the motor right next to the turbo.

Thanks for the feedback guys

Where are you located? SA :confused:

how exactly did you test? did you pressurize your intake?

Huge loss of power.
 

hey before you go racing again lean that thing out to 11-11.5 air to fuel ratio you cant keep the engine cool by running it rich that job is for the oil,coolant and spark plugs. cheers

Yes we pressurized the intake with 1.5 bar and no leaks what so ever.

Running that fat on race gas could foul plugs fairly quickly. I'd try another set.

Also, whats the vaccum like? you said its stable, but is the reading the same as always at idle?

seeing that its a 96, Im guessing he means SA = South Africa.

Yes the vacuum is the same as always at idle. Gonna try a new set of plugs and see what happens, if it is the plugs, its crazy what a negative effect they have on power when fouled up.

SA = South Africa.

Problems I have had causing a big loss in power before without affecting normal idle or driving power, vacuum, etc.

Boost leak (sounds like you checked)

Excessive gap on spark plugs (center electrode worn or ground strap if that type)

Spark plugs loose

Warped apex seals (hot start problems on this one though)

Change in state of tune (like correction maps making you even more rich when you
are on edge of what you can ignite because weather, voltage etc changed).

BLUE TII ,

What you say about the mapping has always been a suspicion of mine, the battery died on the car and after that I this all started happening. I run an Apexi Power FC but I doubt the ECU would have lost or reset the mappings.

If you tuned the car initially with low voltage the ecu SHOULD have been widening the injector pulse to compensate with its voltage/fuel correction map.

If you then raise the voltage back up the ecu SHOULD likewise correct and drop pulse width so you are not more rich than initial tune.

The Power fc MAY not have correctly compensated in either case though leaving you with richer than tuned A/F ratio.

??something easy to check??

Thanks for the help.

Will check it all options suggested above and give feedback.

chip seal
 

Never did a comp test as I was ready for a ported motor and new it was coming out. I was very suprised when I saw how small the chip was in the top of the seal. it looked like something went into the motor and got caught between the seal and housing causing a pencil tip sized chip-scratch in both surfaces.

I was at the track runing high boost and my clutch let go on top of 3rd ger. Over reving -boosting. Car did run bad right away but it was because I blew off a couple of vac hoses.. So it did not just happen for no reason.. Best of luck...

Good advice, I lost over 100HP with a bad set of plugs, they would idle just fine but once I hit 30psi, the power was not there.

Anthony

+1 - My tuning experience tells me that when we start to march below 10.7/10.6:1 that we begin to rapidly run the risk of flooding the motor and knocking it.

I say try a compression test. Something may've happened unbeknownced to you.

B

Couple that with too much timing retard and the resulting misfire on a higher horsepower application and there goes an end housing or apex seals in the worse scenario. You can run that AFR and much richer with the proper igniton but it's also application/horsepower dependant.

BoostedRotary check the turbo for excessive play. Make sure the compressor wheel is not making contact with the compressor housing.

fouled plugs, or apex seal springs that have flattened due to excessive heat from oil washing....

Running that rich without premix will cause you to wipe the oil off of the rotor housing walls and the apex seals. this casues premature wear on the seals and also causes them to get hotter which then flattens the springs.

look for pitted or eroded areas on the leading edge of the apex seal, and flattened apex spring seals. it looks like damage from minor detonation but in reality is caused by overheating of the apex seal from loss of lubrication

kenn

Im sorry mate. But the above post is way off.

With the correct ignition you can run the above fuel mixtures, with premix without, OMP or without.

Why do people post when they have no clue?

Thanks for all the feedback guys.

Regarding the chipped seal, surely your motor wont sound 100% with the seal damaged? My motor sounds and runs 110% (except for power loss of course). My HKS dump valve did break its internals and I hope nothing went up into the motor.

Time for a compression test.

What should a healthy motor read with a compression test?

Have a look at the turbine wheel , I have seen overly rich mixtures coupled with retarded timing , cause the edges of the turbine blade to melt away ! although you see the boost the response is slower and the actual volume "pushed" is less.

hmm....... something like this ;)

http://i152.photobucket.com/albums/s...omaddes011.jpg

At least 7 bar/100 psi on all faces.

Also, have you checked to verify that your leading plugs are firing?

I have a new set of HKS 10.5's arriving in a few days so will drop those in and report the results. My T04Z has only done about 460 track miles and the blades look sparkling. Also going to lean the car out to 11.5 AFR on the dyno once the plugs are in.

Thanks for the help.

No problem.

I don't mean, 'are your leading plugs bad?'

I mean, 'are your leading plugs firing at all?' ie bad coil or bad ignition amp if it's powering the leading coil.

kind of a shot in the dark, but it would explain your problem.

GoodFella,

I havent checked that yet, but its definetly something I will do.

Thanks,

Hi Guys,

Changed plugs and car is 100% again. Happy it was so simple. Now for a lean out.

Thanks for all the help!

Classicauto and I called it :)

I've learned in this past year the answer is sometimes so simple....

This brings up another item on why race plugs foul so easily sometimes.

Anthony

No clue???? check your PM's I will keep this at the PM level.

kenn

Because they are cold plugs. They need high temps to be cleand out properly. I had a set of NGK 11 Iridum plugs fail on me after 4 hours of idle and small driving while tuning vacum. Changed the plugs and all was fine. So driving the car easy and having it idle alot will make the plugs foul out if the tune is rough.

It's all about the tune, but the racing plugs do foul faster then the stock plugs ofc.

I change plugs before ever race weekend. And if no race weekend every 1000-1500 miles.

JT