Power coming and going at high revs...

[SideShowBob]

Hiya
I have a \'93 Type-R, and am having an issue where intermittently, from around 5k rpm up to the buzzer, power will rise, fall, rise, fall all the way till you change gear, then do the same in the next gear.

It feels like it starts pulling, then its as thou power has dropped, then it will get spurts of power as you keep going towards the shift buzzer.

Ive checked coolant and oil, but am at a loss as to what else may cause this.
The difficult thing is that its intermittent, so hard to nail down, so wanted to find out if anyone had experienced anything similar. Below 4.5/5k rpm, it never has a prob, but pushing on from that is when it occurs.

It has induction, peformance cat, exhaust and ecu, if that helps diagnose anything.
Cheers for any ideas.
Graham

[J4P RX]

My car was doing similar.  Thought it was a boost problems.  Turned out to be a misfire and new plugs has fixed it.

Lee

[SideShowBob]

Thanks Lee, been wanting to change the plugs anyway, so will order a set and try that.

[20B_boy]

Plugs are worth a try deffo. I\'m presuming you dont have a boost gauge? If not, get one. If its boost problems the gauge will highlight them in all likeliness. Mine has similar problems; intermitently I will make:

no boost at all, or
make .75 bar which drops off to not a lot, or
make and hold 1 bar

This can happen in 2nd, 3rd, 4th or 5th. Generally if I let off the gas and then reapply it I will make boost again....

In addition to this I can her BOV or W/gate doing its nut, dunno whats happening. All bloody annoying. Sure its a cooked solenoid or popped hose or some thing along these lines.

Fortunately I\'m ditching the stock turbos etc imminently so I\'m not that worried about it now :-)

Good luck,
Rich

[SideShowBob]

I do have a boost guage, what should I look for on it? (im new to turbo\'s)
It does flicker small amounts, as in doesnt rise completely smoothly, but I assume thats normal, but what should I see on it as I go through the revs? considering im running stock boost?

[Fish]

Bob, depending on the vintage of your car, you should see the following boost pattern.

MY92-95 = 10-8-10 psi
MY95-02 = 12-10-12 psi

14.7 psi = 1 bar, so 10 psi = .8 bar and 12 psi = .9 bar

Might also be worth checking how clean the air filter is, this can also restrict boost.

Dan

[SideShowBob]

Thanks Dan, its a \'93 Type-R, so at 2.5k revs, it should be at 10PSi, then drop to 8Psi, then at 4.5k, when the second turbo comes on line, it should go to 10 again and stay there, is that about right???

[20B_boy]

Yep, thats about right bud.

R.

[Fish]

Yeap, expect to go back to 10 psi AFTER 5000 rpm.

Dan

[SideShowBob]

Some more points, could these be related?
The car idles at well over 1000RPM, and doesnt drop below this. The car loses coolant all the time, and needs to be topped up after every drive, a huge plume of smoke is emitted from the exhaust when starting, and it idles poorly for a long while, then when warm idles better, but still doesnt feel well.

[20B_boy]

Are you a member of FDUK? only rather coincidentally a guy on there has just described the very same symptons as these - sounds scarily like water seals and time for a rebuild....

[SideShowBob]

That was probs me, im trying all avenues, really dont want to have to rebuild!!

Is it the symptoms expected in that case then? imagine being without it for most of Summer, wont be happy.

[mmilner]

Originally posted by SideShowBob
That was probs me, im trying all avenues, really dont want to have to rebuild!!

Is it the symptoms expected in that case then? imagine being without it for most of Summer, wont be happy.

The water seals on my FC went a few years ago. I faffed around for months trying to nail down the problem for definite. Continually lost water, poor starting, overheating....

Eventually, (thank goodness), found an oil/water emulsion on the spark plugs which confirmed the problem. (Just like a blown head gasket on a normal engine.)

Booked it in for a new engine with Hurley Eng. in coventry and got it back in around a week. Sorted.

Martin.

[clive]

l am afraid l agree with Martin , sorry but you have lost a water seal as you have the symptoms for this which will mean a rebuild .

All the Best Clive
e-mail: clive@mazdarotaryclub.com
web:    //www.mazdarotaryclub.com

[SideShowBob]

Thats not good then, going in for a full service to see if its fouled plugs, or fuel filter, maybe ill get lucky and it\'ll clear up the problems, but you all sound pretty confident it a rebuild :confused:

Okay, so the bad symptoms are:
It idles at 1300-1400RPM
It emits a large plume of smoke on startup
It idles very rough, and backfires a lot ( may be normal? aftermarket backbox/cat)
Power delivery seems low, and after 4.5k rpm it pulls in fits and starts, and doesnt pull cleanly at all, power comes on and off, althou it appears to be worsening, and power is staying off more than on now.
Coolant goes down very quick, and the buzzer comes on a lot, and I need to fill it up lots (may be a split seal on the bottle on the very left (drivers side) of the car, as it has this black seal around where the tube part meets the bottle part (highly technical description), and this is split as it leaks water if I try fil this bottle, would this cause loss of coolant?)

The GOOD "symptoms" are:
I have stopped it after running for a couple minutes, then restarted it, and it starts (thought a bad engine wouldnt start if run for only a couple mins?)
It has 56k miles on, so a little (only just a little) early for a rebuild.
It hasnt been serviced for a while, so may be all clogged up, so service would give it a new lease of life? (okay, that one was clutching at straws, but Im a desperate man!!)

Right then, from those symptoms, is this almost without question a rebuild job? or is there a chance it just needs a good service?

Thanks
Graham