4agze engine problem - hesitates under load...

[Duk]

Your plugs look the same as the 1s I just changed, but I don't think that will give you a real good indication of what's really going on.

[allencr]

I don't see anything on that site that would give you an idea that your plug looks lean!
Try closing the gap to lighten its load to find out if your ignition system isn't capable of running this thing. It looks a bit wide from here.
What's the compression, wet & dry?????????????????????
*************************************************

Compression is std, 8.9:1 i think.

Getting that answer to a "What's the compression?" question about an engine/driveability problem always leads me to believe that there are going to be more serious problems with the engine, and the owner!!!!!

[mookschank]

Will check actual compression when I take it in, wet & dry, don't have gauge myself. I assume my engine builder would have checked this, however will confirm with him. Theoretical compression ratio is 8.9:1

Gap of old plugs (in pic) are 1.1mm, and had put in 0.8mm gapped ones as per gze spec, no change to hesitation....

[inertia]

Changed coil packs to see if it's them? Ignitor?

Bigger injectors plus a piggy back?

See if the injectors are maxxing out, can you take it to a performance shop to have this done?

I've got an sc14 in the shed that i'm planning on using one day, also have the 7mgte injectors to go in.

[Elfin7]

Sounds very similar to a problem I was having with my clubman.
Running really sh*t under load when coming onto boost and bucking like you said. Also would overheat for no reason. Turned out it was an earthing issue, took it to an auto elec who re did the loom and now it's been running sweet ever since. Not sure if this will be your problem but thought it might help you to know.

Cheers.
Rich.

[NME308]

Ok, might look at the wideband route, will take it to a shop and check A/Fs. The thing is, there's not a lot to tune for A/Fs...? And I dont want to play with the AFM screw as the car was running ok prior to the rebuild (and prior to spinning a bearing).

Hi there,
What is the timing running at? Have you had a timing light on it? I dunno if the 4AGZE has a rubber inserted balancer with possability of spinning and allowing it to read incorrectly either...

Where I am going with this is that the pic of the plug seems to show a fairly high timing mark i.e. the point to which the white colour has moved down the earth strap (oh, and I agree with someone above that the plug gap as measured by eyecrometer is too wide for a boosted motor on stock ignition!). You mentioned briefly your old engine spun a bearing - which can easily be accomplished by detonation as a consequence of too much timing!

You seem to have covered the basics of fuel and air flow meter etc.etc... Weak ignition as mentioned above can also give the same symptoms as lean fuel too, I major to timing first as it is more likely to destroy the engine than a weak ignition!

Cheers,
Jason

[The Witzl]

If the AFM GZE has a knock sensor.... then i would be almost certian that the knock sensor is picking up engine knock and retarding your ignition timing accordingly. The result is you hit boost, plant your foot and the engine revs slowly but makes fuck all power.... it might even make more power on half throttle.

Some time on a dyno will confirm or deny this.

You really should just upgrade to an aftermarket ECU.
Microtechs and Adaptronics are cheap as chips these days. They will solve your problems and will probably net you a more driveable and more powerful result than even a correctly working stock ECU on your modified engine.

[mookschank]

Thanks for the replies folks.

Earthing sounds like something I should add to the list.
Engine was built by a reputable 4ag nut and I would think he set the timing spot on.
We thought about knock sensor but it doesn't feel like pulling timing kind of feel, especially when it sometimes bucks me off the seat
It will be on the dyno early next year to see if we can pinpoint the issue...

Yes, aftermarket ECU is on my mind, just trying to get good running prior to this in case some sensor or other problem will still be there post aftermarket ECU...

[mookschank]

Thought I should update this post as I found the solution to my problem - woohoo!

I finally installed the front mount intercooler prior to an aftermarket ECU install (had an ARC topmount), and voila, hesitation problem gone!

Car runs fine, differently, shitloads more power and now the SC14 is friggin loud!!! Easily outscreams loud exhaust on WOT, all roots goodness though (Having two thoughts about putting the aftermarket on now....)

The moral of the story - SC14+4agze - never use a topmount ;-)

[old_mr2]

Hey Mate

got any pics of your engine bay?

[mookschank]

I can but is there anything you want to see in the engine bay? Reason I say is the SC14 is buried down the side so engine bay looks like any other 4agze? Or are you interested in cooler piping? (Have put SC14 install pics on twincam.org.au site....)

[old_mr2]

just after install pics mate as I am fitting one soon to my aw11, got a link to the twin cam pics for me?

[old_mr2]

found your thread mate on twincam cheers!