serious but weird problem, garages are stumped

[robbie33]

hi folks, im rob, this is my first post, and last hope to be honest

this is an incredibly weird problem, but serious as its put me in 2 (almost) crash situations

i have the mk3 mr2 02 plate 72000 miles, lots of reciepts and 8 service stamps, i bought it 1 year ago and although minor teething probs, 02 sensors, precats out and a bad injector seal. everything was great till 6 months ago.
at cold, it would not rev up, any thing between tickover and full throttle wouldnt work (at the peddle) it grumbled along as if running on 3, but put the foot right down, then the engine note changed to normal and off it went as normal.
this i found was highly dangerous at junctions, roundabouts etc as there was no power at pull off, the only way to get her moving was to put the pedal right down. at which point full power came on, wheel spins etc.
i had an engine light on that was p0141 02 senser bank1 sensor 2 heater failer. that was replaced as was b1 s1 that looked old anyway.
ive had no engine light since, but this problem persists, grumbling, lumpy engine, no power, it seems to improve when i reset the ecu by disconecting the battery.
it also seems to get much better when the cars engine is hot. but if i stop at a shop for  10 mins, the problem returns for a mile or so.
also, very strangley, on occasions when i pull away in first gear, the rev counter can hit 6000 but there is little accleration, until of course i put the pedal all the way down then i get the 6000 rpm all at once
clutch problem ? yes, i pump the clutch and nothing happens.
but testing the clutch and all seems fine again ?, it stalls when i try it, its not the clutch.
i took it to a local garage which charged me £100 basically to change the spark plugs ~(i changed the plugs 3 months ago)
although much better, the problem is still there
its hesitating and theres still flat spots in the power delivery, at the lower rpms upto about 2500 revs.
but if you really give it some, its fine
im not a silly driver and have no need for revs into the 5/6000 rpm band but i do like responsiveness at lower levels.
however when the engine is warmed up, its fine, mostley, but it can still grumble, when in traffic or on slow roads like its not liking being fueled when it should respond to the amount of weight i put on the right pedal. dont think this is a knackered engine, when it goes, it really goes !
this is such a random and unexplained/problem, noone has a clue, its not fun to drive, it cant be sold and id hate to see such a lovely car being made into burnt coke cans
.
im at my wits end, please help

oh, ive cleaned the maf, its looks like it should, even so this wouldnt explain why it runs fine when hot or when the right pedal is right down even when cold.
my dad mentioned a faulty choke sensor, sounds reasonable if the 2 has one but surely it would throw up a cel ?

[krazysteve]

Hi, have a look at this thread you make be able to find something of use.
 l viewtopic.php?f=11&t=34816 l

[loadswine]

It could still be the MAF sensor, as they do die eventually and take note of intake air temperature in their operation. Might be an idea to see if a member near to you could test swap maf with you to eliminate that. The crank position sensor is another gem, but not sure whether the fault with those is temperature dependant like your problem. That thread could provide clues though.
Good luck with it.  s;) s;)

[Anonymous]

Another one for maf as full down is a different loop on the ecu.

[Anonymous]

I vote for knackered MAF,I have a spare you can try and I am taking a trip to Whetherby on Sat morning so could pop by on the way back to try it if this is any good to you?

[Anonymous]

Im happy to send you a MAF sensor. Dont pay if it doesnt work. Or come over and try one here. Ive got throttle bodies, sensors, ECUs.  Eventually the offending part should be eliminated.

Or, Charlesworths (in Charlesworth), east of Manchester are 2 specialists. Not far from you.

[Dyn-Evo]

If its not MAF-related (no1 suspect most times!), it sounds to me like idle valve (ISCV) related, or possibly throttle position sensor (TPS)...?

If the ISCV is clogged / jammed, etc, it will not deliver what the ECU is trying to tell it to deliver.
Also, you may have a vac leak / perished hose, etc, somewhere in the ISCV loop.....it could be electrical, also, but unlikely...more likely to be mechanical-related...?

I dont have a 1ZZ in my car, so can only go from previous MR2 experience, but it sounds similar to something my Mk1 SC did for a while.......  s:wink: :wink: s:wink:

[Goeman]

Hi, have a look at this thread you make be able to find something of use.
 l viewtopic.php?f=11&t=34816 l

It doesn't sound like it's the same problem I had although it doesn't mean the crank sensor isn't at fault.

I feel for you Robbie. It's annoying as hell when you don't have a fault code to tell you which sensor is screwing you over. Take  sdick dick sdick 2ski's offer of a MAF and work your way through the sensors/valves from there. It sounds like the TPS but I can't explain why it fixes itself when the engine gets warm. A garage will probably rape your wallet because it'll require a lot of time and a lot of trial and error. Good luck.

[Wabbitkilla]

There're a few of us around Yorkshire and I'm sure any of us will lend you our MAF for a test drive.
Shout up if there's a way we can meet up with you.

[frogger]

As above - look at the intake tract.

Thats MAF, IACV, and *any* air leaks / gaps in the tract along the way.

Also - pumping the clutch pedal does not a test of a clutch in any way shape or form  s:) s:)

[K T M Rider]

its hesitating and theres still flat spots in the power delivery, at the lower rpms upto about 2500 revs.

i don't really think you need someone else to tell you to try changing the MAF, but this is exactly how my old car felt untill I did just that, although I did get a couple of error codes that helped point me in the right direction (along with this forum). Suspected MAF problems do crop up fairly regularly on here.

this is such a random and unexplained/problem, noone has a clue, its not fun to drive, it cant be sold and id hate to see such a lovely car being made into burnt coke cans
.
I'm at my wits end, please help

Sorry to hear that this has got you pulling your hair out, hopefully this thread is already a help. Just thought it was worth pointing out that if the MAF does not solve the issue and you are running low on patience / finance to continue, you most certainly CAN sell your car (and probably at a fairly reasonable price for a  10 year old motor needing attention) you would just need to describe the fault in your advert that's all.

Ebay often has several examples of MR2 roadsters for sale needing attention - knocking crank bearings being a fairly common theme.

This board is a mine of information if you have the time and patience to wade through it, you just need to search on the relevant terms in the search box (top right of page)

e.g.

TPS;

 l search.php?st=0&sk=t&sd=d&sr=posts&keywords=tps l

ignoring the ones about the Telephone Preference Service   s:) s:)

[redarrow]

I had the same problem and it the clutch in the end.

I also tried cleaning the MAF sensor with no luck, maybe a new one might sort your problem but if the MAF sensor has gone then your surly get a error code.

I also had to get a obd tester for the car, only £15 form ebay inc p&p

I also had to change the o2 sensor behind the drivers side.

In the end, i had to have the aa out, to see the problem and he agreed it was the clutch.

At first the car was pulling as the car got hot, but the more i drive the car no matter what gear i am in, with revs heigh, the car stays still with no power, doing only 10 mph.

I new my self it was the clutch, because as i went up hills the car would need really heigh revs to even move, and i was holding up traffic and it looked stupid in a sports car and not able to move quickly.


Hope you get your car sorted.

if it is the MAF expect some o2 changes as well.

ps.When you said you cleared all the error codes via tacking the battary of, how long did you wait for the codes to be deleted.(I recommend 20 minutes.)
 

all the best redarrow.

[Anonymous]

It doesnt sound clutch related,I would think your mechanic would have diagnosed it if it was.Sounds more electrical,you may be getting a code but the EML light has been disabled/blown so does your engine management light come on with all the other dash lights when you turn the ignition key but not start the engine?

[Steve Green]

I've never heard of a clutch slipping then suddenly being fine and then slipping again. If the cluch was faulty you would have the same general symptoms every time you changed gear.
Add to that a nasty smell as the clutch plate steadily burns.

[robbie33]

hi folks, firstly id like to thank you all for your help, its awefully friendly here.
i doubt its the clutch as well but it seems strange when the engine revs, the power doesnt kick in and depressing the clutch has no effect?? odd. but this happens rarely and i can tell when its going to do it, applying full throttle remedies the problem an gives instant power corresponding to the rev counter, which can be scary. instantly going from nothing to 6000 revs can be.
anyway im gonna go with the MAF a mechanic i took it to went right to it, but without an engine light (and yes it does work) he couldnt really do anything.
also the O ring on the MAF is broken does anyone know the part number ?

many thanks once again folks.

[loadswine]

O ring part number is 90099- 14141. Let's hope you get a result matey.  s;) s;)

[Anonymous]

D!ck2ski has a link to a parts list in his signature a few posts up.

[robbie33]

ive ordered another maf and o ring. but even if the maf is buggered it still wont explain why it works when hot, but not always. the local garage is useless, just looked at me with a blank face when i mentioned the iscv, which sounds a likely culprit as well. can anyone shed any light on this valve ?

[robbie33]

the car is fine at tick over, and starts with no problems at all. its only when you attempt to increase the revs, when in gear any more than slight pressure on the accelerater will cause it to grumble. i DID have a throttle position sensor problem a few months ago, but i tracked the tps down, and found the connector wasnt properly plugged in, a new one of those is probably the next port of call. at this rate it would be cheaper to buy a new engine ! its also been mentioned that the fuel pump could be at fault ? or fuel filter ? blocked injectors ? so far this has cost me £350 in labour and a few unneeded parts.
if the new maf doesnt work can anyone recommend a garage that is familiar with the mr2 in the south yorkshire area or the cost for a new engine ?

[spit]

Hi Robbie.

Its an odd sounding problem you have that seems to fit some but not all the features of things that we've all experienced. Swap-out of sensors and valves is, as Goeman says, a sensible route.

I'm a bit late to the party, but if the MAF doesn't cure the grumble/stumble and you want to look at idle valve and TPS, shout up as there are a few of us with spares kicking around that work and there's no sense in you parting with any money when you can do a trial & error swap-out with friendly Club members. Most will be happy to lend you a hand to keep another '2 on the road.   s8) s8)  

if the new maf doesnt work can anyone recommend a garage that is familiar with the mr2 in the south yorkshire area........

If swap-outs fail, this could be your next port of call. I don't know about SYorks, but Charlesworth motors (Charlesworth nr Glossop) have already been mentioned and they're not too far from you. These guys are ROC-friendly and are painfully familiar with the '2! And they love a challenge. Be sure to let them know you're in the ROC to get the best deal and the friendliest banter.

..... or the cost for a new engine ?

I think it'd be an over-reaction at this stage to be thinking about a new engine.....particularly if the fault is due to a control component that isn't behaving well.

On the temperature thing, I've seen sensors break down or improve with heat when they're on their last legs, particularly where coils and resistor tracks are concerned. That'd include your TPS, Idle control, Crank and cam sensors, so there could be something in that. But again, don't throw money at it unecessarily - Club members can help you out with all of these things.

On the revs, you do have manual transmission and not SMT? Is that right? I'm guessing so from what you've written so far.

Keep plugging away. You'll get there with it.

[robbie33]

thankyou sir, this problem has been ongoing for months now, sometimes it gets better, other times it down right dangerous, im on call with a new warehouse at work so need wheels all the time, ive a spare car for emergencys only, but cant afford to run both. or have the 2 in a garage with mechanics who think spark plugs will solve all her problems !
i really dare not take her far, besides im a little short to spring for hotel rooms while shes being fixed as ive no way to get home.

[spit]

No worries. If you can survive by sticking to the swap-out route without disrupting your work commitments you may well find the answer without resorting to a garage.

Where in SYorks are you? There may be a member on your doorstep willing to provide some more immediate hands-on support.

[krazysteve]

Where in SYorks are you? There may be a member on your doorstep willing to provide some more immediate hands-on support.

Are you close to Chesterfield? w/ends are best for for me.

[robbie33]

new maf went on yesterday (big thanks to  sdick dick sdick 2ski, great price fast delivery) reset the ecu and all was well for 30 mins-1hour. then back to grumbling, although not as bad as it was, however it usually gets worse and worse untill a ecu reset is again needed.
icsv is next, so its back at a (different) garage on monday.
from there its tps, crank position sensor, fuel pump, injectors, coil packs, it can go on forever ! im beginning to wander if its the reason its had 8 owners ? and the car is just 'a bad one'
also the reason im thinking new engine ? as ive already spent £385 on this and im no closer to a solution
i dont think im near chesterfield, but thanks for the offer, besides i darnt risk driving it far, its just to unpredictable
i shall post my findings, if any from the garage monday.
once again, thanks to everyone for the advice, its given me more ideas than i had

[aaronjb]

UK car or import?

If it's a UK car then, based on the symptoms (gradually worsening performance & running until an ECU reset) you need to plug a decent diagnostic tool into the car and check:

1) The short and long term fuel trims when it's running badly - I have a hunch that they are probably way off what they should be (i.e. they should be close to 0%, the ECU allows - from memory - 40% adjustment before it lights the CEL which is an enormous margin for error)
2) The MAF voltage at idle and various RPMs
3) The O2 sensor behaviour

My suspicion would be that erroneous O2 sensor readings (either because of a leak into the exhaust or purely due to duff O2 sensors) is causing the ECU to learn enormous fuel trims - so big that they cause bad running. Based on the symptoms I'd say it thinks the car is rich and it's leaning off the mixture until the engine begins to stumble (16-17:1 at idle is where it'll start to struggle).


If it's an import then you're knackered, sadly, and down to random component swapping  s:( s:(  Though I'd start with some brand new O2 sensors from a known reputable source (not eBay!) assuming you replaced them with generic sensors last time?