Hestitates around 3000rpm

[Iain]

So 20XE engine running on standard injection, standard spec rebuilt engine bar high compression pistons/Cometic gasket...

If I'm flooring it it seems to pull fine, but if I'm tootling without much throttle around 2800rpm it seems to misfire/hesitate then go again.

At first I thought ignition timing as my 1.6 did the same once and this cured it, but it's not adjustable on a 20XE?

Any suggestions/sensors I can try?

[MK999]

I take it it's dispack then? Do they run a knock sensor? As that should retard the ignition if it's knocking which would cause the hesitation, not so much the misfiring though? If it's got a knock sensor and it's working it may just be backing off as much as the map allows already with your high comp pistons. Bear in mind the standard management will be for standard compression and it's more likely to knock running higher.

[General Baxter]

its an xe, you need to redline it for 10mins,

im not joking ether lol

[Iain]

It's a distributor engine, early 20XE? I tried timing it up by rotating the dizzy and it made no difference at all, read that its controlled by the ECU somehow?

It does it pretty much every time you get to that RPM, would knocking be that predictable?

[MK999]

Under the same loading conditions? Actually, just realised you said it's when you're off the throttle, it shouldn't be knocking then. Maybe the TPS? if you're off the throttle and maintaining the same revs you're gonna be at about the same throttle position, maybe it has a dead bit in the track and it's flicking between 0 and part throttle.

edit: also only the advance is controlled by the ECU afaik, runs a similar system to E16SE? Mine made a pretty vague difference on the 1.6 but it was certainly noticable.

[Iain]

Not sure, there's naff all movement available on the dizzy tho?! Maybe 5mm rotation available?

Good thinking, TPS is attached to the throttlebody next to the throttle switch? I may have removed this to clean it, is there any angle/setting up to do on refitting?

[MK999]

If it's the same as the E16 it will have a 'switch' at 0 that clicks, it should be resting on the off setting when the throttle is closed, ready to click on as soon as the throttle moves. Should be covered in haynes?

[Iain]

Will have a sneaky peak at Haynes then, cheers.

[Iain]

I have changed the TPS and set it so it clicks as soon as the throttle linkage moves

I've also swapped the "RON Plug" to side B as I'm using super unleaded.

It still does it occasionally, especially if you don't gun it off in 1st and try and take it steady.

[Rich]

You using an early non lambda loom? They are a pain, you can adjust the air/fuel mixture on the afm but needs to be setup properly or you will just be guessing.

[Iain]

Yes early non lambda. I do have a lambda bung welded into the exhaust so I could get a wideband on it and twiddle that? Does it just the entire mixture or just idle mixture as doesn't the 1600 just do idle?

[Rich]

yeah it adjusts the mixture, usually has a big flat spot and will pull later on but not like it should

[Iain]

Anyone got any more suggestions before I check AFR (don't have a wideband at the mo)? It's either getting worse or I'm booting it off the lights less often and it's quite annoying!

[Adam]

I wouldnt mess with the afr screw tbh, not without it on a RR and a wideband. Do you know what the CR is up to now???

Do you have any spare bits you can try and swap? (coil etc?)

[Iain]

I think CR is up to 11.3.

Thinking about it I have two spare AFMs so might try those, not sure if I'm using the AFM that came with the loom/engine.

[Adam]

Thats quite high tbh for a standard map. Like said, it might be the knock sensor making the ecu drop ignition advance off.

Worth swapping a few things if you have them laying about tho.

[Iain]

True, are you saying the only way to fix it is ITBs & management? Hmmmm lol

[Adam]

;) and whilst youre down at Jenvey pick me up a set for being such a good friend :)

[Iain]

Sure thing hairy one

[Iain]

New AFM has fixed it, drives beautifully at low RPM now, no ITBs for us now Adam :(

[Adam]

Damn :(

See, always worth swapping bits one by one! ;)

Come visit mine sometime, i cant remember what the inside of a nova is like lol lol

[Iain]

OK I'll come and convince you you want yours back on the road lol

[Prey]

Yup - she drives bang on id say....

But get a bigger wheel - felt like driving a kettle kart lol....

[Iain]

You drove it with the 'problem' still in place! Only occurs on cruising/low throttle tho so obviously didn't notice it lol

[Iain]

It's doing the exact same thing again now. Hesitating very badly 2-3000rpm on part throttle. Really bogging down.

Still fine when I boot it but in this weather it produces a ridiculous amount of tyre squeel so not a feasible solution lol

It seemed fine until I put Tesco super in it (99 RON?) - drove like crap and gone back to Shell Vpower in the hope it would go back to normal and it appears not to have.

[Iain]

Bump this is annoying to drive now! XE novelty must have worn off as my foot isn't welded to the floor all the time maybe? lol

[Mieran]

My mate had similar problem, he changed the fuel rail and injectors and it was fine afterwards.

So could have been either the injectors, fpr or the rail.

[comptoncj]

Have you tried basics like are the leads on the plugs securly and not arcing, have you tried running it with the hall sensor on the dizzy unplugged? has it got any trouble codes in the ecu? there was a thread a while ago about an xe going flat at 3k it turned out to be knock sensor wiring that was the fault.

[Iain]

Hmm I have fitted some cleaned cream injectors to it fairly recently. Did his drive OK on full throttle tho?

comptoncj I haven't tried the dizzy sensor unplugged, I'll give it a go after PV. No ECU fault codes.

[scott.parker]

Sounds well annoying mate, i only ever had a similar thing when i had a split sfi box, but your not running one...

And on mine when the coil pack was faulty also.

[Iain]

Yeah it is a little annoying for cruising around town, at least it's fine on full throttle I guess lol

[Iain]

Unplugged the dizzy and it got worse, but having had a wiggle of the HT leads it may have improved. If that's the cause that's quite embarrassing but at least it's an easy fix!