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engine boggs at high rpm (SOLVED)

Sat Feb 27, 2010 4:05 am

hopefully someone on here has solve this problem already. okay. its drive just fine and idles just fine as long as i keep it under 4500rpm. once i take it above that the car boggs and kicks like a fuel cut. but no light and car continues to drive if i keep it under that rpm. boost is set at 10psi using tworus boost controller. gauged with blitz dual tt. no mods at this point on vehicle besides hybrid supra turbo. all suggestion are welcome.
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Last edited by yamayuki98 on Wed Apr 07, 2010 11:47 pm, edited 1 time in total.

Re: engine boggs at high rpm

Sat Feb 27, 2010 4:09 am

Maintenance? How old are your ignition components and your fuel filter?

Re: engine boggs at high rpm

Sun Feb 28, 2010 3:21 am

sorry i should have made myself clear. the car has new oil, new plugs (bkr7e-11). i have both the magnecor 8.5kv wires and the stock (tried both). new rotor and cap. motor was rebuild with new factory valve stem seals, cometic 1.4mm mhg. fuel pump is supra TT pump brand new from factory (not used). fuel filter brand new (factory). timing is correct compression is right on. like i stated idles and drives just fine under 4500rpm. boost perfect too, problem only when i take it above that rpm. i know what boost cut is and its definitely not a boost cut because it does not throw a cel. sometimes the car would just stumble really rough trying to get up to 7k rpm other times it will bogg and throw me back and fourth and continue to climb but slowly. all suggestion welcome

Re: engine boggs at high rpm

Sun Feb 28, 2010 3:41 am

Check your AFM? When did this problem start? What may have changed?

EDIT: What are you plugs gapped to?

Re: engine boggs at high rpm

Sun Feb 28, 2010 3:58 am

Fuel cut certainly does throw a CEL. However, it is pretty hard to mistake it with anything else. If you can rev higher, though it stumbles while maintaining boost, it's almost certainly an ignition or timing issue.

Usual stuff-- check for codes, check your base timing, plug gap, and coil.

Re: engine boggs at high rpm

Sun Feb 28, 2010 9:34 am

Could be an odd fueling issue too... running lean.

Re: engine boggs at high rpm

Sun Feb 28, 2010 9:42 pm

+1 on checking the base timing. I was set at 0*TDC and after 4k, the car would buck and spit fuel out of the exhaust. Once I set the timing back to 10*BTDC, it was fine. Pulls all the way up to the redline now.... No problems

~bloodMoney

Re: engine boggs at high rpm

Mon Mar 01, 2010 2:48 am

thanks for the suggestion. it definitely feels like timing retard. i will check my afm on my days off. plugs are gap at .028. i also ran iridium non gap and still the same thing. timing is right on. no issue on ignition timing. a while back i had some issues running the walbro 255. i now changed it over to the supra tt pump after engine overhaul. fpr resistor on the ecu board was fried so i had to replace it. im wondering now if it could be that the fuel relay is not switching into hgih mode. ill try bridging fp/+b and put it in high mode to see if it helps. i will let you guys know this week sometime. and again thanks. all suggestions are still welcome

Re: engine boggs at high rpm

Mon Mar 01, 2010 4:26 am

boost leak that cause major richness???tmic or fmic???

Re: engine boggs at high rpm

Mon Mar 01, 2010 5:37 am

hm, maybe check your pump relay for switching. check for boost leaks thats a good one. also make sure your tvis is opening

Re: engine boggs at high rpm

Thu Mar 04, 2010 4:02 am

thanks for the suggestions. haven't the chance to diagnose it because my wheel bearings went bad. took it to a machine shop and they said hub needs to be replaced. quoted $192.00 just for the hub. i went online and got it off conecilli for $128.00 shipped to my door. still expensive though. back to the topic yeah, me thinks its also a boost leak somewhere. still using top mougnt. maybe need to check for vacuum. thanks i will try and get this sorted out asap once i get the hub and wheel back together.

Re: engine boggs at high rpm

Wed Mar 24, 2010 7:18 pm

check to make sure your ignitor has a good ground and is the right 1 for your car
the wrong ignitor will make your engine cut off at 4500rpm
check the flapper door on your maf to make sure it moves smoothly
check for trouble codes?
try this...remove the vaccum line to your map sensor...plug it and see if it helps

Re: engine boggs at high rpm

Thu Mar 25, 2010 2:19 am

your spark plugs.. bkr7e-11 doesnt the 11 mean the gap is 1.1cm instead of the recommended 8mm?? that would give you a bit of a prob, but i wouldve thought it wouldve been during all driving conditions

just a thought

Re: engine boggs at high rpm

Thu Mar 25, 2010 5:13 pm

The 11 corresponds to a .044" gap or 1.1mm which is far to large for our application. But he said he gapped his plugs to .028" so i dont think that is an issue.

Re: engine boggs at high rpm

Thu Mar 25, 2010 6:02 pm

hows your coil?
check the resistance

primary coil resistance: .4-.5 ohms
secondary coil resistance: 10,200-13,800 ohms
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