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Discussion Starter · #1 · (Edited)
Hi, guys.

Was doing 75 MPH on motorway yesterday when all of a sudden I was doing 95.

Couldn't get the car to rev down, so had to get to a safe place by sitting on the brakes and forcing down the gears until almost stall...very smelly.

When I start the engine it jumps to 3500 RPM and sits there.

Have checked acc pedal, thottle assy, butterfly inside the TB and had a friend hold the throttle closed on startup, all with no change.

Also looked at all hoses I could find and replaced the cracked one that goes to the side of the induction kit.

Only other current issue with the engine is the fuel pump won't work unless I keep TEN-GND jumped - am waiting for a new switching relay.

Any urgent suggestions? Will sit on this forum until an angel appears! Bear in mind I've just lost daylight so am limited in what I can do or see...

* Update: Have unplugged the white connector under the TB as Oddball suggested in http://www.mx6.com/forums/united-kingdom-ireland/217612-idle-swine.html, but no change. What does this mean? Is is significant? *

Thanks,

S.
 

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If the throttle butterfly is closed and held shut, then the engine is getting its air from somewhere else. Pull the PCV valve off the fron rocker cover and see if it stalls, or if you notice any strong vacuum at the PCV valve or the port on the rocker cover.

You could try fully tightening the Idle air screw (count how many turns you make) and see if there is any difference(if no difference turn the screw back the number of turns you counted).

The IAC/BAC could be jammed fully open, but i dont see why this would happen all of a sudden whilst driving as the coolant would be hot and the valve virtually closed.

Check the pipe you say you replaced from the intake elbow to the metal pipe running along the back of the rear rocker cover, and the smaller rubber pipe elbow joining the metal pipe to the rear rocker cover .. pic below..

Also check for codes, and see if the engine does the same in diag mode, ruling out any faulty sensors.

 

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Discussion Starter · #3 ·
Will try them all - the pipe I replaced is a smaller-diameter one that meets a silver sticky-out pipe on the side of the induction kit itself.

Don't know how to do the 'diag mode' bit, or checking for codes.

will do all the rest, and be back in 10 mins.

Thanks,,,,
 

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Discussion Starter · #5 · (Edited)
apparently sorted...

Thanks, Paul!!!

Checked all the big pipes - ok.

Started up with PCV valve out - no suction and it didn't stall.

Screwed throttle stop screw (between both parts of the spring-loaded assembly, right?) back 20 'corners' and started up, and bingo! Screwed it back 10 more corners and idle seems to be where it should.

Will take it for a drive, to get the idle set right and take it from there.

All I can guess is that it was at my 'friends' TD Autos last week and they must have changed it.

Reset ECU last night whilst diagnosing so that should help too.

It seems that I'm running the car in permanent diag mode at the moment anyway, or the fuel pump doesn't work!

thanks again - looks ok for now, but I'll keep you updated.

Strange that it didn't stall with PCV valve out...Christmas Gremlins...
 

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ok so its ticking over where it should.

Its not the screw i ment, but good job you tried it, with you saying a friend had held the trottle shut, i assumed you had checked the butterfly was seatign fully closed. That screw you turned has a lock nut around it. This need to be tight to stop it rotating, which is probably whats happened. Its become loose and with vibration, managed to turn itself inwards and hold the throttle open.
 

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Discussion Starter · #7 ·
hmm...no lock nut!

Just the screw itself. Where can I get one of these nuts?

Thanks again.....
 

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Take a look at the pics in this thread, does the adjustment screw look like this ? ..

To keep the screw from turning, dab some sealant or similar on it. Something that will withstand heat though, as the throttle body can get quite hot.
 

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Discussion Starter · #9 ·
Erm...yr link's not a link - try again?
 

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Discussion Starter · #11 ·
Nah, not the big cross screw in top.

See the u-shaped bit between the labels for A-A and B-B in the first picture, which has got a banana shape cut out for the throttle cable's connector to move up & down?

Well there are two of those, and the lower one sits against a screw mounted to the upper one on idle. I can take a pic if you like, but it's that screw.
 

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Discussion Starter · #13 ·
I think so - not too clear!

Hope this is ok as a temp to mid-term fix - as I said, that screw hasn't got any nuts on it.

The one referred to as the throttle linkage adjusting screw is one I didn't know about - but don't wanna mess with anything more than what I need to have it running ok!

Maybe we should have monthly or quarterly 'car doctor' niggle-fixing meets!

Going out now to see how she runs.

If you want to email [email protected] , I can get it on my iphone.

Thanks again, back later on, either by car, or by recovery truck again!

Typical that this would happen when I've got so many miles to cover, and when the Skyline's stuck in the garage, waiting for a bank transfer from my ppl in Japan to arrive before they'll release it to me!
 

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Discussion Starter · #14 ·
Update:

I messed up on the info provided: Was driving with f/p and GND jumped, not TEN and GND!

BUT my replacement switching relay finally arrived (thanks again!!!), swapped it out and now fuel pump works without the jumping.

Idle is now around 1500 or a bit more, as will adjust the big screw on top of the TB as soon as I can be bothered to take off the strut brace to get to it...

Yes, it's a bored TB but I'm hoping just adjusting this screw will sort it out? Have had it running with a good idle for a while since the TB swap.

Don't really wanna start messing around with the fan and feeler gauges again unless I really have to.
 

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Discussion Starter · #15 ·
Ok, here's the latest....

Took the strut brace off, and started engine, with a good idle - typical.

Tweaking the throttle, and the idle settled back at the higher level.

Looking at the throttle assembly, it seems it's not sitting back on the screw that appears to be a part of the TB housing, in the centre of this photo - you may be able to see the gap.

When I push it back to touch it, the idle goes too low, to a stall.



The vertical screw in the middle of this next picture is the one I adjusted back to get the idle down from 3000+RPM last week. Looking at the colouring on it, you can see how far in it was adjusted previously, as I said, around 5-6 full turns - madness!



Today, I've adjusted it right back until the spring-loaded throttle sits down on it, in other words, it's raised enough to make positive contact, but not enough to actually lift the throttle. The idle seems where it should be now. Will run the car for a bit, and keep checking back here for any further advice.

Thanks, as always!...
 

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Sounds like the butterfly is sticking/fouling the bore if you can push the lever back and the idle settles down. Best to take it off so you can backlight it, and make the adjustments so you dont see daylight around the butterfly or can see where its catching and clean it up.

Good to see the GPO only took 3 weeks to deliver the relay ... god bless the postal service :rolleyes:
 

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Discussion Starter · #17 ·
Could well be...I remember when I got it back from having the butterly made (Tb was bored locally to me, butterfly done through Suppliers on here), there were bits of space to be seen all the way around - not a snug fit at all.

Anyway, it seems that by random processes I've got the idle behaving, maybe a tad slow, but that saves fuel...})

Thanks again for that relay. PM me what I owe you and how to pay!
 
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