not another 4age turbo question - fat missfire during spool

[Paulio]

hi

i am now having to deal with a horrible problem my levin has aquired. heres a description:

just after spool and before full boost (8psi) with the throttle to the floor (not really, but enough to hit full boost), what seems like a fuel cut happens, a loudish missfire and the engine check light comes on, power drops for half a second when this happens then continues to boost as normal. it either does this before full boost or doesn't do it at all, generally in 3rd and 4th gear, 5th too. seems like its when there is greater strain on the engine at higher speeds.

heres some specs that matter:

redtop 4age non-tvis, strengthened internals, slightly larger injectors with a powerlink powering two additional 465cc injectors before the tb. standard ecu, 7s plugs, t3/t4 turbo, all the normal stuff on the outside.

as far as I think, the ecu can't fuel cut and when the missfire happens the engine check sensor comes on as if the knock sensor reacted.

possibilities: cams jumped a notch, timing slightly out but have check all this and the obvious stuff.

next step if no solution is found: get a link and do a data run, solve it that way.


any suggestions are very much appreciated

regards
paul

[~SlideWays~]

Have you tried colder spark plugs?

[Paulio]

shit, thats the other thing I forgot to mention. it has never had this problem until my mate thrashed the shit out of it.

no I havn't tried any different plugs at all.

[~SlideWays~]

sh*t, thats the other thing I forgot to mention. it has never had this problem until my mate thrashed the sh*t out of it.

no I havn't tried any different plugs at all.

Go get some NGK's in 8 range. Standard for 4agze is about 6 depending on the brand. I had really bad missfiring after more boost/link/speedtech tune and it was just the spark plugs.

EDIT: I just noticed you said "7s plugs" i assume you mean the heat range is 7. either way its only going to cost you $20 to get a new set and cancel that out of the equation.

[matt dunn]

the engine check light comes on,

First thing to do is check codes then.

You will need to drive it till the fault happens and the light comes on then pull over and check the codes without switching off the engine as not all codes get logged into the memory under all conditions.

[TRD_ZERO]

I had the same issue with my ep71 turbo it cut out when it hit around 15psi and the engine light came on(pretty scary). This only happend in the higher gears when there is load on the engine this caused it to overboost. Is your boostguage working properly? Maybe u have a boost leak and ur boosting more than you think you are. Im just guessing here, so hope this helps.

[big_boy]

-weres your base timeing set
-what fuel do you run

as all thoes bits sound like its pinking

-the loss in power can be both stright pinking looseing power & the ECU retarding the timeing
- pinking normaly happens at W.O.T. & in higher gears
- pinking will offen let alot of gas down your exuast (hence the back fire)
-& the check engin light may be comeing on as the knock sensour car give weird signals when it gets pinking not detnation then when it gets normal signals it will turn off

just a thort

[Paulio]

I had the same issue with my ep71 turbo it cut out when it hit around 15psi and the engine light came on(pretty scary). This only happend in the higher gears when there is load on the engine this caused it to overboost. Is your boostguage working properly? Maybe u have a boost leak and ur boosting more than you think you are. Im just guessing here, so hope this helps.

i've tapped the boost closed so its suppose to be set at 4psi, i'm sure it isn't overboosting. was your problem caused by boost leak?

thanks

[Crampy]

heres some specs that matter:

redtop 4age non-tvis, strengthened internals, slightly larger injectors with a powerlink powering two additional 465cc injectors before the tb. standard ecu, 7s plugs, t3/t4 turbo, all the normal stuff on the outside.

as far as I think, the ecu can't fuel cut and when the missfire happens the engine check sensor comes on as if the knock sensor reacted.

Is it a standard 4AGE computer, or a 4AGZE one?

If it's the standard 4AGE ECU and MAP sensor, they can't run boost properly. It'll fuel cut at around 4psi or so.
If it stock 4AGE ECU, you need to either run the computer in diagnostic mode, or put a check valve in the vacuum line going to the MAP sensor.

If it's a 4AGZE computer, check the timing.

More information is required about your setup...

[Paulio]

Accepted answer:

Get new plugs!

Running like a $&#$% minta now, cheers guys!

[~SlideWays~]

Accepted answer:

Get new plugs!

Running like a $&#$% minta now, cheers guys!

Woohoo go me!

[normality78]

i remmeber i met abt the same problem as you do before. but mine was due to overheated plug and ecu check light indicating knocking.

[Drifter4ag]

yeah ... running hicomp pistons on a boosted motor requires number 8 plugs ...

and if its a standard ecu it should be in diag mode to stop the fuel cut at 4psi

[KE25-KP30]

Sorry for my ignorance, but in a quick word, what is diagnostic mode, what does it do to let it run boost and how do you switch them??

Cheers

[raddies]

yes how is 4age ecu put onto diag mode??

[raddies]

bump

[bluemaumau]

sorry no one answered your question in the minute between 7:57 and 7:58, how may we be of service?

what gen 4age do you have?

[~SlideWays~]

sorry no one answered your question in the minute between 7:57 and 7:58, how may we be of service?

what gen 4age do you have?

[raddies]

haha just getting it up the ladder, ae86 bluetop 16v 4age

[Calvin]

bump

WTF you bumpd your post one min after you posted... Lol. Legend