4AGZE map lagging a little more than expected!! NOW FIXED!!!

[4AGZE_rolla]

hey guys i hav a ae92 map GZE in my ae92 seca sx!! now i wasnt expecting massive powah increases after the conversion but i do notice it is a bit laggy from mid range to top end!! i also have a HKS 164mm pully attached and the boost guage always reads a healty 10psi sometimes 11 when winding 3rd out on the freeway!! it just seems to lack, my opinion is the fuel supply isnt strong enough!! my pump is only stock and has a whine you can hear when the car is idling( could even notice that before the conversion) could that mean its rooted?? and if so would a replacment stock one be good enough or would bigger be better?? i do want a straight bolt in though!!
has anyone experienced this or know whats wrong??
thanks guys!!

[myne]

What intercooler are you running?

Is it response lag, or are you just noticing the power drop off slightly after ~4000rpm?
Superchargers steal a lot of power to run, so torque tends to peak fairly early in the rev range and drop off after that.

[4AGZE_rolla]

its a bit of both!! look put it this way it is slower than when it had the NA 4AGE in it!! on the gtech it ran a 17 1/4!!
it just takes for ever to wind out even to 5000!! it only has the stock cooler!! but i dont think that could be dragging it down that much!! it idles fine and steady at 600. just seems to hav no pull,

[myne]

I'd be going with timing, possibly knock sensor.
I'm running the stock interwarmer with no scoop and mine has no probs booting it.

[BrianRA23]

Mine used to really start to pull around 3500rpm and go hard from there on up so it does not sound right (that was with the standard pulleys. Maybe your belt is slipping.

If the pump is whinning then it might be having trouble sucking from the tank, which could be a blocked filter in the tank or other restriction. I once had a small cube of rubber occasionally blocking the hole in the pickup on an old celica with efi and had a similar symptom. Remove the pump and pickup from the tank to make sure it is all clear as a first check.

To determine if the pump is too small you should take it to a workshop and watch the fuel pressure under load, which should not take long.

If it is an in-tank you should be able to buy a higher rated pump (ebay is a cheap place for them) and then use a hose clamp to attach it to the bracket the factory pump was attached to. Just make sure the electrical connections are 100%.

[oldcorollas]

if you think it is fuel, get thee to a dyno and check AFR's...
if it's pinging, the knock sensor may be retarding timing so you get no power, even tho you have boost.... so.....

check timing, AFR and boost on dyno and then you will know for sure.

[mullett]

From what I've heard, (and I don't know alot about it), the post-5000rpm drop off is a common problem with the MAP GZEs. Might be something to do with the knock sensor? Either way, it's happened before, maybe google can help you out? I think HKS also made a little dongle to help with it, but aftermarket management would be your best bet by far...

RM.

[Mos]

Given you're saying it's slower than the atmo, I have to ask this - are you sure the SC is actually running?
Mos.

[Vios-GT_07]

fuel pump whining? stock fuel pump?? a conversion to GZE.. the first thing u do is hook up a new fuel pump !! Bosch 040 or VL is a pump of choice! then at least u've got that sorted.

hmm. u're making 10 psi sometimes 11 psi.. sounds boosted to me from memory it didn't go that much but yea could be the crank pulley. Definitely not the switch (sorry Mos), and it doesn't look like belt slip. However, idling at 600 sounds off to me.. most GZEs (all in fact) i've seen idle around the 800 to 900 mark.

i'd also agree with oldcorolla in saying dyno, or a AFR gauge would be really useful to determine if u have any future problems and is your best friend in telling you the mix being rich / lean. knock sensors.. hmm.. could only mean your motor has issues so i'd leave that until i've exhausted all other options. Knock sensors could be small news, or bad news..

[4AGZE_rolla]

cheers guys for the responses!! doesnt ping as such but and is always very smooth at idle maybe its closer to 700 then but not rough at all feels like a new car!! so thats why i thought maybe it was lack of fuel because it just didnt hav the mid range power at all!
not so little power like the exhaust was blocked but just a noticable restriction somewhere!!
as to the charger yeah it is definatley working you can hear the clutch grab if you accelerate slow in first, it is boosting and whining if you rev out! (which seems to take forever!! )
anyway gonna try and drop it in today to a tuner and see what they come up with?? i will tell him bout knock sensor and so on!!
thanks again guys!!

[oldcorollas]

fuel pump whining? stock fuel pump?? a conversion to GZE.. the first thing u do is hook up a new fuel pump !! Bosch 040 or VL is a pump of choice! then at least u've got that sorted.

umm.. why not a Walbro/Holley intank pump? the dunnydore pumps are overrated

[The Witzl]

From what I've heard, (and I don't know alot about it), the post-5000rpm drop off is a common problem with the MAP GZEs. Might be something to do with the knock sensor? Either way, it's happened before, maybe google can help you out? I think HKS also made a little dongle to help with it, but aftermarket management would be your best bet by far...

RM.

Mullet is correct, based on my personal experience.
The knock sensors on the smallport (and also some 20v 4A-GEs) are quite sensitive and actually start picking up top end "rattles" and determining them to be knocking - thus the ECU retards the timing and the car drives worse than a piece of p00.....

Of all the LOW-KILOMETER or excellent condition front-cuts i've seen converted, none have demonstrated the "5000rpm drop-off" that everyone claims is "normal" for a 4agze - they all pulled strong right up to 7000rpm.

Your solutions are however limited, if this is indeed your problem. Rebuild the engine, or replace the stock ECU with something aftermarket so that the knock control problem is eliminated.

NOTE: unplugging or unbolting the knock sensor will result in 100% knock control! ie - no ignition advance allowed!


Good luck with it..... oh, and take it to a GOOD workshop to analyse your problem.

[Vios-GT_07]

umm.. why not a Walbro/Holley intank pump? the dunnydore pumps are overrated

yea why not eh.. i've always stuck with easily found oversized things like commonwhore brakes and stuff. the good bits! hehehe..

Of all the LOW-KILOMETER or excellent condition front-cuts i've seen converted, none have demonstrated the "5000rpm drop-off" that everyone claims is "normal" for a 4agze - they all pulled strong right up to 7000rpm.

Your solutions are however limited, if this is indeed your problem. Rebuild the engine, or replace the stock ECU with something aftermarket so that the knock control problem is eliminated.

that makes sense i've driven stock GZEs, one with a stock ECU another with an aftermarket one.. i've noticed the stock one pulls hard but drops up just before redline.. probably 6000 rpm or so.. while the aftermarket ECU revved it hard slightly over 7200 RPM but dyno read power being straight all the way (no drop)

[Hen]

While I think the main problem has been answered, concluding from your symptoms that the fuel pump is not up to the task seems wrong.

If you are running 10-11psi and the fuel pump couldn't supply the needed fuel then your engine would lean out and start pinging its head off. This could easily be diagnosed with a wideband AFR sensor.

Knock sensor troubles are a much more reasonable cause of this problem.

Hen

[AE86 LSG]

Not sure if you have the problem sorted yet but i had two things happen after putting my ZE in my spoonter.
-First prob was S/C would cut in and out iratically, problem solved by loose plug think it was an earth wire not sure.
-Second prob new S/C pulley belt loosened as it wore in so was slipping which equaled shit power and even shiter top end tightned this and was screaming through the gears again.
Hope you get problem solved because these engines just feel awesome when running well they are so different to anything else i have driven, smooth with ballsey torque.....