Mk1 not accelerating

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Mk1 not accelerating

Postby Mac1508 » Thu Sep 15, 2016 10:54 pm

Hi All,

My 1996 Mk1 has acquired a recent acceleration problem ( as in there is none ) foot flat and car barely moves. A month ago she was spluttering so i changed the fuel filter and all seemed ok.

However on top of my already broken oil pump, which is still needing fixed and making a god aweful noise, the car has next to no acceleration, the engine in general is running like total rubbish atm.

any initial ideas would be most helpful, im running out of ideas.

Thanks
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Re: Mk1 not accelerating

Postby Ginger Nuts » Thu Sep 15, 2016 11:09 pm

I've had an issue like this on cars in the past (not an mx5 though) turned out to be the CAT which was falling to bits and causing a blockage in the exhaust, so running like death warmed up.

I assume you have checked the air intakes along with the fuel so I'd check the CAT.

Just my tuppence worth from years of tinkering and good old trial and error.

Good luck.
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Re: Mk1 not accelerating

Postby drumtochty » Thu Sep 15, 2016 11:24 pm

It may be the timing belt has jumped some teeth but if the oil pump is faulty the engine will be scrap by now!
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Re: Mk1 not accelerating

Postby joeytalent » Fri Sep 16, 2016 4:43 pm

Check the basics - fuel, spark, air. If you've got all those, check the compression.

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Re: Mk1 not accelerating

Postby drumtochty » Fri Sep 16, 2016 6:11 pm

So you are telling him to run the engine with no oil pump operating.

I can't believe you are adving that Joey.
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Re: Mk1 not accelerating

Postby Mac1508 » Fri Sep 16, 2016 9:13 pm

Hi guys,

Thanks for all th replies....well we have pretty much solved it. I went to check the oil pump to find the engine would barely manually turn over. That on top of the crank pulley and timing pully having the keyway snapped and broke. I beleive the oil pump Is soo broken it's it's adding ridiculous strain to the engine.

And yeah running the engine with broken oil pump proven fatal.

Bugger.

Attempting to fix tomorrow, don't suppose there is a way to remove sump without removing the sub frame?

Thanks
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Re: Mk1 not accelerating

Postby drumtochty » Fri Sep 16, 2016 11:37 pm

Pretty crap trying to get the sump off.

Not tried myself, but maybe easier to take the engine out as always google it or look on youtube someone must have tried it before.
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Re: Mk1 not accelerating

Postby Mac1508 » Sat Sep 17, 2016 8:46 am

Aye im working on a driveway with a mate, no engine hoist o anything :P

But appreciate the help. Gonna remove sub frame enough to remove sump, got a donor 1.6 that I'm stealing the parts of till I can replace engine....might as well turbo this one now it's days are numbered ;)

Cheers
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Re: Mk1 not accelerating

Postby Mac1508 » Sat Sep 17, 2016 10:08 pm

As an update, oil pump was perfect. Almost brand new....so back to square one.

The crankshaft/pully/timing gear were all chipped from where the keyway had snapped. I think the keyway and all parts being broken wa making rattling noise, and the poor running is attributed to clogged filter. But Time will tell.

As for the work we dropped sub frame no bother, removed sump to remove oil pump to find it was fine and all crank bearing seemed fine but no extensive work was don on them.

Once more into the fray tomorrow.
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Re: Mk1 not accelerating

Postby joeytalent » Sun Sep 18, 2016 11:36 am

I had a horrible rattling noise from the front of the engine as a result of the water pump pulley not being properly seated

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Re: Mk1 not accelerating

Postby Mac1508 » Sun Sep 18, 2016 12:05 pm

Cheers will make sure that is good and tight this time a well
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Re: Mk1 not accelerating

Postby drumtochty » Sun Sep 18, 2016 2:12 pm

1996 cars had the long nose crank so that shows that the long nose crank can have similar problems to the short nose engine
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Re: Mk1 not accelerating

Postby Mac1508 » Tue Sep 20, 2016 9:06 pm

So pulleys fixed, keyway replaced, damage to crank botched with metal glue for time being, rattle sorted.....very happy.




but loss of power still there, we bipassed the fuel filter as we knew that was clogged last time....but alas still next to no power.....driving me mad, need to see what the pressure is in the fuel line. Need to check fuel injectors, but im not feeling hopeful :(

any ideas other than that?
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Re: Mk1 not accelerating

Postby joeytalent » Tue Sep 20, 2016 10:55 pm

Check for a strong spark with all the plugs. Both HT leads and the coil packs are failure points.

Is the idle normal? No higher than normal?

What about the ECU in the passenger foot well? Is that damp?

I'd check the timing as well.

Don't give up hope, you'll figure it in the end.



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Re: Mk1 not accelerating

Postby Mac1508 » Wed Sep 21, 2016 11:57 am

Thanks Joey,

Coil pack replaced, HT leads replaced. Sparks checked.

It can barely hold an idle, mostly i have to keep some revs.
the revs are as id expect so at 60 in 5th its around 3000. but just no acceleration, and VERY hot, so all points to burning really lean.

bought myself a fuel pressure tester, gotta find what choking, maybe the cam sensor causing spark retardation...but i dunno :) she will live eventually.

Thanks
MAc
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Re: Mk1 not accelerating

Postby joeytalent » Wed Sep 21, 2016 12:18 pm

Get some WD40 or carb cleaner and spray around all the joins for the air intake (including throttle body) whilst the car is running. If the RPM dips, then you have an air leak.

Definitely check the ECU for dampness as well - it's common on these cars and can manifest itself in mysterious ways.
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Re: Mk1 not accelerating

Postby Mac1508 » Wed Sep 21, 2016 12:28 pm

yeap got a spare ECU but doesnt even start when using it. it deffinately got damp at one point....entirely my fault :S
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Re: Mk1 not accelerating

Postby Mac1508 » Fri Sep 23, 2016 3:32 pm

update, tested fuel pressure vbefore the fuel rail, running at 2.5 BAr,

according to my haynes tahts less than half
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Re: Mk1 not accelerating

Postby mgrays » Sun Sep 25, 2016 7:07 pm

http://www.miataturbo.net/engine-perfor ... ure-57544/

On a 1.6 but the same thing as a 1.8 NA from memory just different injectors .. they say 35-38psi at idle and 48-50psi at atmospheric... your 2.5 bar is 36psi so looks fine. Ah.. was the Haynes manual dead headed or running pressure? Dead headed is gauge on the end of hose with no flow to injectors.. that should be 75-90 psi off the top of my head.. but running pressure on actual injectors is what you need to know as that is what supplies the injectors after the fuel pressure regulator has dumped the excess pressure back down the return line and is 35 psi odd. The dead headed pressure just tells you about the pump/relay condition under load but could still be achieved with a pretty blocked fuel filter.. ideally you strap the fuel pressure gauge to your windscreen and check the pressure under load/rpm on the road .. as again a blocked filter/compromised fuel pump/relay will be fine at idle/revs in workshop sometimes. Folk tie the gauge to the wipers for road testing .. so no using the wipers when like that!

Running hot - how are you telling this? ..could be lean or timing.. is it pinking.. what colour are the spark plugs.. white hot or nice bit of brown.. or sooty black rich? I used to run car to a fault point (e.g. stuttering etc) then stop engine on ignition with clutch down.. and then pull the plugs to tell what engine is doing at the point of failure. I did have a non stock issue like this where the non stock air temp sensor on my kit "pulled the choke" on and my exhaust manifold was cherry red, miss firing under load and poor outside of it.. not your problem here but it shows that funny things happen if ECU and sensors are not right.

Sort of wondering about Cam timing or TPS (throttle position sensor).. TPS would really only happen if you had messed with it or forgot it. I would double check the CAM timing marks.. check the TDC by a rod through the spark plug hole.. find a 25mm travel point either side of the TDC and then true TDC is the middle of the 2 travel points.. check that on the crank position markers and then recheck Cam timing by googling Miata NA cam timing e.g. this; http://wiki.miata.net/tiki-index.php?pa ... Belt+Steps
TPS is here http://wiki.miata.net/tiki-index.php?pa ... ion+Sensor
No start here http://wiki.miata.net/tiki-index.php?pa ... tart+Guide
.. and then check your idle timing with a timing light if you can.

Done a compression test? could be burnt valve seat/piston etc. They should be even about 180 psi (pull all plugs when you do it).. worry if one is 20 psi different to the ohters. Running lean due to fuel filter might have burnt something .. guess that leads into maybe Lambda sensor being wrong .. you can put a voltmeter on it at the ECU with a lot of care and see if you are getting 0.8V which I think is Lambda (0.6 lean, 1.1V rich).
Here is a Lambda lesson; http://www.miata.net/garage/KnowYourCar/S3_O2.html

Could still be a stuffed/blocked catalytic convertor.. guess you could slack bolts just before it to give 10mm clearance and go for a limited road test. That would choke the air flow and kill power and higher revs .. might kill idle but I doubt it as there is not much flow at idle.

Have you pulled one spark plug at a time to see if one cylinder does more to idle than another one.. hard on these cars as they are lost spark but if you just lightly rest the lead on the plug you can pull one cylinder at a time. (lost spark means one coil per pair of plugs, each plug is an earth and they spark on the exhaust stroke and compression stroke on the pair cylinders).

Just a few thoughts as I am twiddling thumbs right now.. so may not answer right away after this week.
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Re: Mk1 not accelerating

Postby Mac1508 » Wed Sep 28, 2016 9:52 pm

wow , hell of an answer :)

will try to answer all those points.

so to start, compression test done, all within limits on every cylinder.

ino its running hot just as a general knowing my car type deal, the car is just hotter than it normally is, sounds stupid but can feel the heat coming through the foot well and general areas in car...not to mention the engine bay. After running car for very small amount of time the engine is already roasting hot.

Sparks checked and white tipped but black on threads, wasnt sure how to gauge that.

it was a dead head teast, FPG was placed before fuel rail.

I redid my timing to make sure it wasnt a stupid mistake on my part, timing is spot on.

I thought maybe the CAM sensor was on its way out, but the FPG test makes me think fuel again.

I have heard maybe a choked CAT but not convinced, will probably test just to cover bases but my gut tells me its not that, I started getting a ot more fuel for my tank before the power loss, again making me think she is lean.

We have actually bi-passed the fuel filter to ensure its not that,s so even with a clear line she is still not giving me the fuel, again i thought pump but we checked that and appears to be fine, but havent ruled out.

new FPR has arrived will try that plus other stuff see what happens i guess.

cheers for all the input :)
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