NA overfuelling issue

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Bish1999
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NA overfuelling issue

Post by Bish1999 »

So I've been trouble shooting an issue with my new rev 1 MR2 (NA model) and I've had a random thought.

I'm planning on testing TPS and various other sensors and systems such as ignition timing as the car seems to start running very badly after it's warmed up. Very temperamental but once properly warmed I can't do anything more than feather the throttle or is stutters and sounds a bit like a 2 step system.

Its got quite a high cold idle at 1500 but as far as I can tell that's fairly normal.

I checked the spark plugs and it seems as though it's running very rich, brand new plugs that I bought the other day have blackened quite severely around the ring beneath the electrodes.

PO installed an apexi intake system with a cone filter and I've just realise while brainstorming that It doesn't have an MAF or MAP or anything like that? There is a sensor which I beleive to be a flow mass meter, is this the only sensor on the intake system for a 91 NA?

If so how do I go about testing it to make sure it's working properly?

Depserate to work out what's causing it to run like this so I can get out and drive it already :D

Should mention I've got a timing gun coming next week so I can get round to checking ignition timing but I don't see how this would have changed as I haven't fiddle around and undone the distributor or anything like that.

Any and all help is appreciated, apologies if this is a repeated thread at all I didn't have any luck finding anything else like this on the search bar.



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Re: NA overfuelling issue

Post by MRHAPPY62 »

Have you downloaded the bgb ?
could be iscv .
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Re: NA overfuelling issue

Post by Bish1999 »

MRHAPPY62 wrote: 30/01/21 19:33 Have you downloaded the bgb ?
could be iscv .
No not as of yet, been reading through a PDF of the handbook for the car (I assume the BGB is exactly that).
Would the iscv still affect driving though? I would have thought it would only affect the idling characteristics of the car.

Edit: Just thought as well, it seems to start absolutely fine, maybe it gets stuck in the cold start position and won't switch to the running position?
It'll be one of the many things I take off and check regardless.
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Re: NA overfuelling issue

Post by jimi »

BGB = Big Green Book = the Toyota Workshop Manual, not the owners manual
Download from here https://www.mr2oc.co.uk/download-cats/c ... 1-mk2.html
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Re: NA overfuelling issue

Post by Bish1999 »

jimi wrote: 31/01/21 17:27 BGB = Big Green Book = the Toyota Workshop Manual, not the owners manual
Download from here https://www.mr2oc.co.uk/download-cats/c ... 1-mk2.html
Brill, cheers pal
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Re: NA overfuelling issue

Post by jimi »

If you can't find the correct BGB there, try this thread https://www.mr2oc.co.uk/forum/198/80372.html
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Re: NA overfuelling issue

Post by Bish1999 »

Update for anyone with similar problems/symptoms:

The exhaust on the car was installed terribly with sleeve out of the flange bent and basically just sitting on the backbox flange very badly with the front pipe flange bent at an angle to hold it in place there. This obviously put extra load on the ignition leads, which by some anomaly are the original 1991 set, and caused them to lose their insulation altogether despite having in-spec resistance and seeming to be in fine condition.

£30 on ebay for a new front pipe, 10 for the crush gaskets, a few quid for an exhaust gasket and 40 quid on some new leads and the car is running spot on apart from a rather occasional slightly rough idle.

Seems over fueling was never really the issue but nevertheless I'm glad I spent the time cleaning the throttle plate, ISCV and checking the spec of the TPS.

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