Author Topic: Boost issues  (Read 2565 times)

Offline Skifledanabit

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Boost issues
« on: May 19, 2016, 08:12:29 PM »
Hi all,

Just finished at Essex Rotary where Aston spent a few hours doing the TPS on my vert.

I was getting the usual TPS issues, bucking/backfiring/poor idle/etc which have now actually been sorted.

But there was a second issue, when fully warm I will try and boost and it will just not go, it will loose power, backfire and rumble, wouldn't accelerate unless under very light pressure on the pedal, even when the clutch is down it just won't accelerate. It's as though the turbo just says "nope".

Anyone experienced this? Found out what's wrong? It's not the TPS, not the turbo, what is it? I'm flummoxed.


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Offline TiddlesRX7

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Re: Boost issues
« Reply #1 on: June 03, 2016, 04:31:48 PM »
That sounds like what mine was like when I changed my intake set-up before I had it mapped. Maybe check all the air intake side of things to see if there is anything obvious.
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Offline Skifledanabit

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Re: Boost issues
« Reply #2 on: June 12, 2016, 08:48:04 PM »
You'll want to try turning up the volume because the microphone was compensating. But essentially, when I put my foot down, it won't go past that point. Only time it revs up is if I only put slight pressure on the accelerator.


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Offline Skifledanabit

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Re: Boost issues
« Reply #3 on: June 12, 2016, 08:50:01 PM »



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Offline boosted

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Re: Boost issues
« Reply #4 on: June 12, 2016, 09:04:20 PM »
Doesnt sound like ignition braking down...could i suggest fuel stavation?
Dont know anything about the fc but the principles are the same on all engines...
If youve got a good spark then id be looking at fuel pump next.

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Offline clive

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Re: Boost issues
« Reply #5 on: June 13, 2016, 08:30:17 AM »
This sounds more like a plug or a pipe that has fallen off ?????? ???
All the best Clive

Offline Smiffers

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Re: Boost issues
« Reply #6 on: June 13, 2016, 09:54:39 PM »
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...
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Offline Smiffers

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Re: Boost issues
« Reply #7 on: June 13, 2016, 09:55:10 PM »
...was faulty
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Offline Skifledanabit

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Re: Boost issues
« Reply #8 on: June 15, 2016, 01:10:58 AM »
It's progressively gotten worse. I drove it down from Stirling with just TPS issues, juddering when off throttle etc. The next time I took it out it lasted about half an hour before it started doing as such in the video, the time after that it was about 10 minutes after warm up, then the final time was that video I've posted which was as soon as it was warm if not before.


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Offline Skifledanabit

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Re: Boost issues
« Reply #9 on: June 15, 2016, 01:14:27 AM »
Clive, I've gone through and replaced accessible vacuum pipes with silicone, I couldn't find any damage on any of them. However, do UK FCs have charcoal canisters? There's a pipe coming from the bottom of a charcoal canister looking cylinder on the passenger side of the engine bay, up by the bulkhead and this pipe isn't attached to anything, I think it's a fuel vapour dump.


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Offline Skifledanabit

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Re: Boost issues
« Reply #10 on: June 15, 2016, 01:16:03 AM »
Doesnt sound like ignition braking down...could i suggest fuel stavation?
Dont know anything about the fc but the principles are the same on all engines...
If youve got a good spark then id be looking at fuel pump next.

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If anything it's over fuelling. It's chucking out a lot of fuel, with a hefty smell too, even at idle.


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Offline Skifledanabit

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Re: Boost issues
« Reply #11 on: June 15, 2016, 01:19:18 AM »
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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Offline clive

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Re: Boost issues
« Reply #12 on: June 15, 2016, 07:53:55 AM »
Sounds like you already have access to a manual but just in case you didn't know, we have a link to all manuals in the general and technical area.

Real weird one this one, almost sounds like something on the intake side collapsing and blocking the intake when the engines hot as this would give the same symptom you describe.

 http://mazdarotaryclub.com/forum/index.php?topic=66749.0 
All the best Clive

Offline Smiffers

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Re: Boost issues
« Reply #13 on: June 15, 2016, 11:34:40 AM »
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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Offline Skifledanabit

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Re: Boost issues
« Reply #14 on: June 15, 2016, 06:05:56 PM »
Sounds like you already have access to a manual but just in case you didn't know, we have a link to all manuals in the general and technical area.

Real weird one this one, almost sounds like something on the intake side collapsing and blocking the intake when the engines hot as this would give the same symptom you describe.

 http://mazdarotaryclub.com/forum/index.php?topic=66749.0

Yep, got the Haynes and the service manuals.


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