Trouble with boost over 1bar

[topgear]

When I reach 1bar of boost, it's like hitting a fuel cut or revlimiter.
The rpm arrow on the tacho begins to randomly jump from 3000-7000 rpm,
or sometimes at full throtlle hitting 1 bar of boost and 4000rpm in second gear tacho stops @ 4000 rpm mark and speed slowly keeps on rising with a huge loss of power.
If I set max boost to 0.8 bar, nothing wrong happens, everything is smooth and fine.
Almost everything connected with ignition is changed, but still no results.
I`m shure that the problem is with the ignition
but don`t know where
all the wiring checked twise still nothing



Engine 7m-gte `91
mods:

ARP Pro Series Head Bolts
Clevite Main & Rod Bearings
Wiseco Pistons & Rings - 7MGTE - 84mm Bore, .040 Oversize, 9.0 Comp Ratio
Eagle H Beams 4340 Forged Chromoly Steel Connecting Rods
Fidanza Built To Fly Flywheel
RPS Bronze Stage 5 Clutch Kit (Sprung Disk)
Titan Motorsports Head Gasket (Stopper style), 2.0mm
Toga High Volume Oil Pump
//Powerhouse Stainless Exhaust Manifold
Garret GT40
Greddy iridium sparkplugs 9
40mm UnKnown Wastegate
Custom Cooler & Piping
Spearco Intake
Custom 3` Exhaust
PIT Blow off Valve and Flange
Walbro 255lph Fuel Pump
WR Adjustable Fuel Pressure Regulator
RC Engineering 750cc Injectors
Tein Super Street Suspension
Stop Tech break Pads
AEM standalone


:1zhelp:

[suprahabsfan]

First thing I would do is check for boost leaks. My car was doing "similiar" to that, and it was a boost leak. Probably wont fix the problem completely but its a place to start.

[Snotcycle]

who tuned your standalone, you may want to call them up.

[topgear]

no boost leaks (checked few times)

my stand alone tuners tell me that I have problem with wiring
they insist on changing the whole wiring, too expensive, but I did check it for damages, twise, still no result.

[Supra87T]

my stand alone tuners tell me that I have problem with wiring
they insist on changing the whole wiring, too expensive, but I did check it for damages, twise, still no result.

Wiring is probably the first thing you'll want to fix. You can have the harness repaired and tested for around $400. Check with Dr. Tweak in the vendor's section.

[turbogate]

Wiring is probably the first thing you'll want to fix. You can have the harness repaired and tested for around $400. Check with Dr. Tweak in the vendor's section.

I was quoted ~$400 for a brand new harness (1990 car) from one of the forums toyota dealership vendors.

Something you might want to double check. The AEM does have it's own boost cut setting. You can find it in along with the rev limiter/2-step options window in AEM pro. If you have a laptop you can double check whether or not they might have activated it. However I believe it's off by default. But it's worth trying. I have mine set to cut at anything over 21psi and it might have saved my engine the other day when I forgot that my profec-B was disconnected from it's power source therefore allowing maximum(until it blows) boost. boost cut off course kicked in :icon_bigg

[buldozr]

you didnt mention plug gap... blowing out the spark?

[topgear]

AEM`s boost cut setting cant check right now, but dont think its a problem, because I still have 1bar @ 3-4k rpm with no problem but @ 4.5 :aigo:

have tried many settings with the spark gaps, nothing happens
tried from 0.4 to 1.2mm

~$400 for a brand new harness
thats the prise that I`m willing to pay
but here, in estonia, i`m shure it`ll cost 1000$
must check with toyota dealers, cant say if it so or even more

[topgear]

video that I made today
2 gear, pedal to the matal.... as soon as i get max boost, tacho stops & speed keeps on rising, when I get my foot off, no boost & tacho returns to normal work showing me that I was doing 100kmph @ 6500rpm

http://www.hot.ee/caddy041/acceleration.3gp

[IJ.]

Sounds like hard boost cut.

[Mr. Y]

topgear
stop doing that! You'll ruin engine.

IJ.
I almost sure, It's CPS problems. Engine is reving (speed goes up), but AEM doesn't see it (see tacho readings). So we have engine @5K rpms running at wrong tables cell (fuel and ignition). Very lean mixture + wrong ign advance make car behavior like fuel cut.

[topgear]

what to do ?
need instructions:1zhelp:

[Mr. Y]

topgear
Please post datalog file in *.csv format.
RPM, MAP, Ignition advance, AFR, injection time vs time.
Better to post 2 datalogs: small boost w/o "fuel cut" and problematic log.

PS: warning, grab logs at your own risk ;-)

[IJ.]

topgear
stop doing that! You'll ruin engine.

IJ.
I almost sure, It's CPS problems. Engine is reving (speed goes up), but AEM doesn't see it (see tacho readings). So we have engine @5K rpms running at wrong tables cell (fuel and ignition). Very lean mixture + wrong ign advance make car behavior like fuel cut.

It "should" throw a Sync/Ref error in that case.

The Tach thing sounds like Hard Cut.

Moved to Standalone for Joe's input.

[topgear]

with the THING happening I`have wideband showing 11,4

[topgear]

today found something wierd
while was trying to drive outside of the garage
the aem began to shut on & off every second
hearing the fuel pump goes on & off
action was about 15 sec long

what can cause such thing ?


once same day, while driving, engine just shut off by unknown reason, tryed to start, nothig... but after a 1 min of waiting went on like nothing happend.

[turbo joe]

I know you'd probably like to hear that there's something exotic and AEM-specific that's doing it...but it's likely just a loose wire somewhere. Maybe a loose ground connection.

[suprahero]

Maybe a loose ground connection.

That's what I was thiking. My car acted very similar because I didn't have it grounded properly. I added three grounding straps and it purred like a kitten. It was breaking up horribly at around 4500 under high booost. After the ground straps, it revv'd all the way to 7300 without a glitch.

[chevyeater]

today found something wierd
while was trying to drive outside of the garage
the aem began to shut on & off every second
hearing the fuel pump goes on & off
action was about 15 sec long

what can cause such thing ?


once same day, while driving, engine just shut off by unknown reason, tryed to start, nothig... but after a 1 min of waiting went on like nothing happend.

I'd be checking the MAP sensor wiring and CPS wiring. Wiggle all of the connections with the engine idling. If that checks out, give the EMS box the old "tap test". You need to see if it logs a synch or timing error when it does that "boost cut" (after you check the boost cut setting), then go from there.

If the AEM was set for a "hard cut" the camera would have hit the steering wheel in the video. :D It could be a soft cut or a 2 step or maybe they tried setting up the slew rate t/c and goofed it or something...

[turbo joe]

If the ECU turns off...it can really ony be one of two things...the positive wire or the negative wire. That could mean a bad ECU for sure (those two circuits go all the way inside)...but if it shuts off on its own, that shouldn't be hard to track down.

[topgear]

its wire troble for shure
while trying to extract log file, pc tells me that aem ems is offline, but car is working, the once it did log in and after pressing accelerator few times went offline again
where to look for a broken wire
added additional ground to the engine bay

help

(dont have enough $ to go to professionals right now)

[chevyeater]

You can't go by PC comms to see if the EMS is actually online or off. A good clue is the check engine light. The startup calibration for the AEM has it set to be on with the key on and engine off. If the light is off with the key on (and the settings haven't been fiddled) the EMS is likely offline. If the light is on, look at your PC, cable or USB adapter. USB adapters are notoriously unreliable. If the car is running, the EMS is definitely online and your problem is elsewhere. Also, be sure that telemetry for the AEM serial gage isn't activated in your calibration as that will block the laptop comms as well.

[topgear]

can it be that one of the sensors somewhere causing such thing ?
or relay?
wiering rechecked, still nothing:aigo:

[turbo joe]

If you're losing the ground on the fuel pump relay, it's either the ground (the wires themselves) or the thing that switches the ground on (the ECU).

You gotta roll up your sleeves and do a little of that good-old basic troubleshooting. Look for other ECU-controlled (pull-to-ground) circuits and see if you lose those as well.

You should check the 5v reference voltage (5v wire at the TPS would do) and see if that stays on during your problem...that will help to differentiate between a power supply issue (ignition circuit failure, failed ECU etc.) or a logic thing (software in the ECU deliberately switching off outputs).

[topgear]

had to remove all engine harness
found that under intake manifold 4 ground wires that go straight to ecu were losen:cry:
had to repair few broken wires & everything works again:love:

thank you all for help
local mechanics can only put together bimmer

[turbo joe]

had to remove all engine harness
found that under intake manifold 4 ground wires that go straight to ecu were losen:cry:
had to repair few broken wires & everything works again:love:

thank you all for help
local mechanics can only put together bimmer

Sweet. :D

Tell them we said that a real mechanic can fix anything...LOL...a car is a car. :biglaugh:

[topgear]

Sweet. :D

Tell them we said that a real mechanic can fix anything...LOL...a car is a car. :biglaugh:

I`m shure that they `ll tell me:
dont tell us what to do, and we wont tell you where to go:biglaugh:

[Mr. Y]

:1zhelp:
I've got the similar problem right now.
Fresh harness and AEM from Gixxer, car fired ok, idles.. Tuned low load a bit...
But _sometimes_ something strange happens: during acceleration tacho stops for a moment and then continues to rise.... Like 2300, 2400, 2500.. pause.. 2600, 2700... Yes, it looks like fuel cut.

Never then cruising. Only during accel. It may occur at 2500, may at 4500... Sometimes it doesn't occur at all (1 of 10). Enclosed gaps in CPS - didn't help. Checked grounds - they are good (added few more for any case).

So, now the questions:
1) What parameters should I log to check that AEM reads CPS correctly
2) Any ideas?

PS: I'm tuning fuel table and get 3.1 value in it e.g.... What parameters should I log to see how much fuel AEM is squirting actually... in ms.
PS2: I'll try to hook switch to make internal logs. Hope this will help to figure out problem.

EDIT: digged in AEM forums and found "30* problem" that looks like mine. So I'll try to figure out: is it sensor problem (CPS) or actuator problem (igniter). Stay tuned.

[Mr. Y]

some news.
Retarded all map, so max advance is 28* and problem went away but car feels soo slow.

I have 3 channel igniter left from Haltech, so how can I convert AEM to it? It is dumb igniter so AEM will be controling dwell as well... But dwell settings look complicated to me =( Some kind of angles instead of just time in milliseconds.

Anyone converted AEM p'n'p box to run non-mulpiplexed igniter? Please chime in!

PS: grabbed some internal logs before retarding timing and there were some dips in T2PER and cam-crank parameters. Misfire occured when BOTH dropped. After retarding ign, there are still some dips in T2PER or cam-crank but NOT ar the same time. Any thoughts about this?