Boost issues

[Skifledanabit]

Yep, often electrical faults do that, could be the sensor circuit rather than the sensor itself etc...

It is certainly worth checking all the connections... also try disconnecting the MAP and see if the behavior is the same, would give you a clue if that is causing the issue.

Is there a MAP sensor?... the boost gauge does not seem to be responding with your throttle movements as I would expect?

If the MAP was not faulty it might be OK under high vac (low throttle) but not under lager throttle positions...

Could the sensor deteriorate over a short amount of time? Such as be fine for half an hour, then play up, then be OK after restarting but quickly fail again? It certainly has a sensor behind the air box but which type of sensor it is, I'd need to check the manual.


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What should I expect? Smoother running? Worse?


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[Skifledanabit]

I just swapped the AFM unit out for another one and left the car to warm up. Turbo is coming on and the car is revving nicely. I decided to go for a quick boost test drive.


It was boosting beautifully, no hunting, no power loss or juddering, no over fuelling, just a good drive. Until halfway up the road...



Limped it home, then took that video. On very light throttle and no turbo, it revs up but as soon as I try and actually get the turbo spooling, it just chokes up and splutters.

So it's not the AFM, I don't think it's a vacuum issue;
could the turbo be naff?
Exhaust blocked?
I'm just unlucky with cars?


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[boosted]

Does the fc have an old skool diagnositic plug? Where you put an led or light from ground and test point in plug and count the flashes to give you the fault code...ive used it with success on a mk1 mx5.

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[boosted]

I had a quick google and there is a way to get some codes out of the ecu.
It was over on fc3s.org....you may have more luck having a search on there...good luck stick with it.  Where abouts are you?


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[Skifledanabit]

Does the fc have an old skool diagnositic plug? Where you put an led or light from ground and test point in plug and count the flashes to give you the fault code...ive used it with success on a mk1 mx5.

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Yes it does, I'm not overly keen with electrics though so I'll need to either beg someone to do it or force myself to do it.

I had a quick google and there is a way to get some codes out of the ecu.
It was over on fc3s.org....you may have more luck having a search on there...good luck stick with it.  Where abouts are you?


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I think I've seen it about. I'm in Romford, Essex, near Essex rotary. I might need to steal Aston for a bit after coaxing it over there, or trailer it.


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[Skifledanabit]

The upper trailing plug, similar condition to the upper leading plug. Note the oil round the threads.



The two lower plugs...



Calcification?


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[Skifledanabit]

It's not the TPS, I've replaced the spark plugs, leads, trailing coil packs, fuel filter and swapped out the TPS sensor itself. Idles beautifully now but I'm still having these bloody issues when hot.

Reckon there's a sensor that throws it into limp mode if the intake temp is too hot?

Any other ideas?


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[clive]

Wow, you did a lot last night,

 I know we pushed a few things around, so reading this, maybe swap out the ECU with the other car to see what happens     

[boosted]

Any joy with getting codes out? Also could still be dieing fuelpump...change it as a service item to x of list? Or there are gauge kits on ebay cheap that you can hook up to see pressure on a drive and on load.

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[Skifledanabit]

It was the OMP by the way.


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[boosted]

Interested to know how you found the issue?

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[Skifledanabit]

Interested to know how you found the issue?

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A cross between fault elimination and luck, RX7Club had a thread saying all different kinds of things including the OMP.

I eventually decided it was limp mode. after checking the air, fuel and ignition, the next step was the oil. so after one last check on google and RX7Club, I decided to check the OMP anyway because it was the most likely culprit in the oil system, bingo, there was some sort of insta-gasket crud in the recess.

[boosted]

Nice 1 fella....its always great to know the solution...
Enjoy your boost.

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[Casey]

Well done for finally nailing the cause and fixing it 

[spizwalt]

i know im bring this old thread up but just wanted to say im going to try this out on mine, have a very similar problem, so this may solve it.

thanks for posting what it was that solved it.

Will