Splattering/Missing under load >10 vacuum

[vas85]

Hi Guys,

Did some research but it seems to be a maze of possibilities from what I've gathered so far as to what may be going wrong here.

My car has been running perfectly fine with no mods done to it in the last year other than a full service (all bets + filters) in the last year.

What is happening is that under any load greater than 10 vacuum (according to my boost gauge) it will splatter/miss but it doesn't back fire.

I can drive the car to 3000-4000-5000 rpm and hold it there without any problems if I get it there slowly but if I give it WOT or anything above 10 vacuum it seems to stutter and splatter in its process of building up the revs.

All I have done recently is removed the power steering reservoir and bracket along with the cables that plug in at the thermostat housing and afm.

I'm pretty stumped over this as my coolant isn't leaking, temps are at 72*celsius as they've been all winter and there are no oil leaks.

I tried to get some good vids depicting what is going on but the sound doesn't seem to come through properly so that you can hear what I'm referring to.

Any ideas guys?

Happened like that out of nowhere, and my PPS reservoir clean-up was a week before this just started happening.

 

[jdub]

First - Read this:
http://www.cygnusx1.net/supra/TechTips/vacuum_gauge_readings.aspx

Second - Do you have any ECU codes?

Third - Coolant temps of 72 deg C means the coolant is never getting in the 80-100 deg C ops temp range. The ECU is staying in warm-up enrichment. Pull the connector off the ECU temp sensor and give it a run, report back on that. (check for codes 1st)

 

[vas85]

First - Read this:
http://www.cygnusx1.net/supra/TechTips/vacuum_gauge_readings.aspx

Second - Do you have any ECU codes?

Third - Coolant temps of 72 deg C means the coolant is never getting in the 80-100 deg C ops temp range. The ECU is staying in warm-up enrichment. Pull the connector off the ECU temp sensor and give it a run, report back on that. (check for codes 1st)

Thanks JDub,

I've so far read the vacuum gauge radings guide and also checked for codes.

ECU only reported code 51 - switch signal which has troubled area's as tps circuit or tps, ecu or a/c.

Don't know how that relates to my problem?

I'll drive it tomorrow without the ECU temp sensor and report back on how that goes.

Thanks again.

 

[vas85]

Driven the car with the ECU Temp Sensor unplugged and it drove the same as far as the splattering/missing.

What I then tried out is lower the mbc from 13psi to factory psi levels and the car seemed to run slightly better. I took out the MBC and then the car would drive fine to 6psi but anything after it would hesitate in buildling more boost.

Any idea's guys?

I thought it may be to do with the way the MBC and auxiliary hoses connected suspecting a leak but took off the intake hose before the turbo and all that to have a peek and couldn't see anything wrong.

Put the MBC back on and set it to 13psi and >10 vacuum it hesitates to build boost but can now make it several psi (<6) before it hesitates.

Oddly enough, no milky foam in the oil cap, no oil or water leaks and other than cleaning the power steering reservoir haven't touched her in any other way.

Any idea's guys as to why I now can't seem to build >6psi? If I modulate the throttle gently to say 2, 3, 4, or 5 psi she holds perfectly and power delivery seems normal.

 

[vas85]

Driven the car with the ECU Temp Sensor unplugged and it drove the same as far as the splattering/missing.

What I then tried out is lower the mbc from 13psi to factory psi levels and the car seemed to run slightly better. I took out the MBC and then the car would drive fine to 6psi but anything after it would hesitate in buildling more boost.

Any idea's guys?

I thought it may be to do with the way the MBC and auxiliary hoses connected suspecting a leak but took off the intake hose before the turbo and all that to have a peek and couldn't see anything wrong.

Put the MBC back on and set it to 13psi and >10 vacuum it hesitates to build boost but can now make it several psi (<6) before it hesitates.

Oddly enough, other than cleaning the power steering reservoir haven't touched her in any other way.

Any idea's guys as to why I now can't seem to build >6psi? If I modulate the throttle gently to say 2, 3, 4, or 5 psi she holds perfectly and power delivery seems normal.

 

[vas85]

Hi Guys,

Had a week off on Holiday and then had the car booked at my local Mechanic, and the problem of splattering/missing under load was due to the spark plugs failing... gap was larger than spec and the leads were also shot.

FYI for anyone else experiences what appears like power loss/vacuum issues it could possibly be what I had go wrong with mine.