Odd one! flat spot/restrictor when accelerating hard round a left hand turn.

Started by tommytoneism, October 29, 2018, 19:08

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jonbill

#50
December 19, 2018, 08:26
Sounds like a good plan.
I might be wrong but my recollection is that MAF value should be just over 2 at idle.
If right and your MAF is good then I think it still indicates you've got an air leak after it.

I'll check mine later and see what it runs at...

shnazzle

#51
December 19, 2018, 08:59
Maf values look OK to me. Everything checks out for idle.
Just the top end (wide open throttle) look a bit high.

Cold idle has a higher rpm and more advance with a bit richer mix, which is spot on. Then when warm timing reduces to 14.5-15 and rpms to 750-850 with what seems like stoich. fueling. So that's good.

I had one more thought; it seems that when you let off throttle suddenly is goes into a sudden rich condition and inversely when you floor it, it goes lean (which is when you had your knock). This is as expected but the ecu compensates. Well... It SHOULD. But on yours it seems to struggle.
The only way the ecu can compensate for that is by reading the TPS (it's really the only time it uses the TPS signal much). So... What I would try, to isolate the TPS, is do a full run in 3rd on the motorway from as slow as you can (pulling onto motorway) all the way to 6k rpm or so. But do it very progressively. That way it won't use the tip-in map for sudden throttle.

If it pulls fine, the TPS would be my next bet before all else.
...neutiquam erro.

shnazzle

#52
December 19, 2018, 09:04
PS if it is the TPS then I've got a working one for you. For free
...neutiquam erro.

tommytoneism

#53
December 19, 2018, 11:22
That's brilliant thanks, I'll keep you posted. :D

tommytoneism

#54
January 7, 2019, 20:21
 :-[

           Ok so seems to be sorted, but I'll explain how I got there.  Little bit embarrassing :-[ because after my frequent removals of the air intake (DIY job having used the original MAF housing) and saying that I couldn't find the leak...Well, :o I found one. As most of you will know, where the fins are, and where in the OEM set-up meets the filter box, there is a sliding movement across the pipe just before the box where the two meet.  This had play on mine as I'd left this section in when I cut it up. So with certain lateral g, it would let air in. Admittedly this is before the MAF but obviously enough to confuse it. This is why on a couple of occasions where I had floored it coming in to my village , it had moved a lot more, and suddenly started coughing and stalling, and then I couldn't start it!

            So I re-cut the mounting and made sure there was no leaks.. put it all back together and it ran great, but 15 miles or so and it just did it once again..not as bad and only once..  I then read another forum feed about a similar issue where he believed it to be the fuel pump, I was going to change my pump but when I took it all apart I realised you had to do bit of modification of the housing to get the pump in. So I just settled with changing the filter and left the original pump in. The other thread had mentioned that he also threw in some redex and v-power. So I did the same and changed my map on my Dastek for the v-power...and hey presto..it's going like a rocket and no bogging down.

             So here are my conclusions...

    1. the worst of it was coming from changes of air into the intake because of movement from lateral g.
    2. Possibly some crap through the fuel system and injectors
      3. and, but not sure, possibly a fault in the normal unleaded map caused by running it with the first fault..?

                 The knocking noise, which came and went,  I pinpointed to the charcoal canister..

    Thanks again to everyone that has helped me through this :notworthy:, and I hope this helps someone else. ;)

    As a suggestion, it might be an idea for those who can run off spreadsheets of data of their cars running well, to start a new thread and post, so that it can be a source of comparison..what do you think?

    Thanks again,

    Lance

shnazzle

#55
January 7, 2019, 21:38
Woohoo! Good news. Glad it's sorted.

If the mr2 had a proper refresh rate on the obd2 readings we would have noticed the MAF readings being erratic. Unfortunately, the granularity is piss poor and you have to be lucky to catch something.

A leak that close to back of the maf might as well be a leak in front of it. It disturbs the airflow massively. That mixed with some bad fuel and there's your misfire.

Onwards and upwards!
...neutiquam erro.

jonbill

#56
January 7, 2019, 22:38
Glad it's sorted. I knew it was an air leak :-)

tommytoneism

#57
January 29, 2019, 22:19
 :'(

I pulled into the garage the other day to fill up...no high octane.. so normal in, switched map back to normal fuel..problem started again!! just craps out at 5k..but it's intermittent!  doesn't do it when it's cold! So when I could I put v-power back in,, switched map to high octane..still did it!!  :'(...   intermittent.


What's going on..! :-\
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