Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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Hi all. My recent engine conversion in my Corsa SXi (1.2 16V Ecotec) to an X16XE engine setup went great. All running fine, but not exactly smoothly. I have just one issue, which I hope you guys can help with.
Just so that you know from the start, the engine spec is: - Piper GM reprofiled cams, Mantzel inlet manifold, Janspeed exhaust manifold, decatted custom straight through exhaust system, GM airbox and feed with K&N panel filter, Splitfire plugs, Kerr Racing leads, lightened and balanced flywheel.
When driving the car sensibly it runs like a dream, no problems, with the odd exception. But in general, when try to run it past 4-5k RPM or when I quickly stamp the accelerator to the floor the engine comes accross some problems, it kind of chokes and no matter how hard you press the accelerator, nothing. You have to release it again as if to let the engine catch up before you can apply the throttle to pull away again. Which I found to be very dangerous during some overtaking moves tonight
At first I thought that the engine wasn't getting enough air, so I removed the airbox temporarily and covered the intake with a sock securely. Took it for a drive and that just made it a hundred times worth, even on low revs it was choking every 5seconds, hardly driveable.
So I put the airbox back on and cheked around all of vacuum hosing making sure of no leaks. Did this and found nothing wrong in that department. So am now stuck. I am getting a slight whiff of fuel through the blowers into the cabin and wondered if it was overfuelling, running rich.
But with the engine running the way it is, I suspect that it may be running lean (which I know is not good). The only thing I haven't changed on the car relating to the engine is the fuel pump and fuel filter. I have a new fuel filter and am yet to put it on. One lad told me today that he suspects that the X12XE fuel pump isn't man enough for the job when it comes to the X16XE and that's why i'm getting the symptoms, and the engine is most likely running lean... but why the smell of fuel in the cabin?!?!?!?!?
And another lad told me that the fuel pump in the SXi is the same as the 1400/1600 fuel pump. So.....
....Quite simply, I don't know which way to turn.
*Are the fuel pumps the same?
*Does it sound like the engine is running rich/lean?
*And what do you guys think is causing the choking?
Appreciate any kind of feedback on this people. Cheers all. Kyle  
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lee mitchell
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Registered: 26th Jan 01
Location: kent...drive's: eveyones conversion cars hard lol
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pump is fine for the engine. take ur plugs out and see wot colour they are. white is lean black is rich
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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OK will do tomorrow when it's lighter. Engine has had a rebuild and only run for 1000miles, so will I be able to still tell from them?
Also, if it is lean - what's the cure?
and if it's rich - what's the cure?
Any ideas about the choking?
Was thinking a remap may help as still on standard management.
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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didnt get it sorted then mate
if its running rich or lean then its likely to be lambda or coolant temp sensor.
although, as i said on the phone its more likely to be map sensor related. another thought i had was that it could also be the throttle position switch.
is it throttle related or revs related?
way to tell is to raise the revs slowly whilst idleing until it chokes/ tries to cut out. note the revs it does it at.
then drive at say 40 in 5th then open throttle fully. does it do it then?
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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No mate. Not sorted. Alot better than it was mind. When the engine is idling and not in gear the engine will rev without any problems mate. It is only when the car is in gear and going that I get the choking/trying to cut out.
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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Also, do you think my existing fuel pump is definitely upto the job?
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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is it just when you floor it?
does it do it if you raise the revs slowly whilst driving?
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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That's a hard one to be honest.
It GENERALLY happens when i'm cruising along and then drop the accelerator to overtake for instance and it occurs around the 4-5k rpm range. Like it can't cope with high engine speed, which is why I thought it to be the fuel pump.
But it has been doing it to me a few times (but not as often) when I change from 1st to 2nd cruising, and happens around the 2500rpm mark.
But generally I can drive it well without too much problems raising the revs slowly, until I get into 5th gear where it will almost always do it.
[Edited on 09-10-2005 by Tiger_kpt]
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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did you check for air leaks? also, disconnect the vaccum hose from the cam cover and see if it still happens.
(will make a hissing noise, but dont worry about that. might help find out whats wrong though.
on another note, be carefull if its just been re-built
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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Second that mate. Just took her for a test-drive again. I can drive her fine easing the throttle on bit by bit, or putting it on moderatley, but as soon as I plunge the accelerator it chokes badly. And even when I change gear up during the choking period, it still chokes in that new gear until I give it time to "recover" so to speak. Think that has defined it down better.
I tried that earlier mate. I disconnected the head breather vacuum so that only the fuel pressure regulator, Mantzel inlet and Map sensor were vacuumed in. And still no change. I have even blanked off the spare port on the throttle body to make sure. Not sure about the MAP sensor. Idles fine with it plugged in/vacuumed in. But as soon as I disconnect the vacuum pipe to it it runs like a bag of sh*t, even on idle, so would have thought that the MAP sensor was working.
Also checked for air leaks yeah. Can't feel or hear anything from the various hoses around the head and inlet.
[Edited on 09-10-2005 by Tiger_kpt]
[Edited on 09-10-2005 by Tiger_kpt]
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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my money is on an incorrectly fitted vaccum hose or a leak somewhere.
secondly i would look at throttle position sensor or map sensor. (got both of these spare here mate) borrow them if you want to try them.
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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Definitely no leaking at idle. Sure of it. Seems weird how the engine can rev well out of gear but not in gear. Will try that again tomorrow just to be sure actually.
I even disconnected those two components you told me to earlier in terms of unlinking them from the vacuum hose linkage and unplugging them from the loom, ran alot better without them to be fair, even though ECU light is on. What components were they? One with the yellow/white valve on and the one with the triangualr metal fixing on?
The thing that I was thinking is that maybe that blue vacuum hosing is a bit flimsy. Seems no way as strong as the regular black vacuum hosing. You think that may be it??? As in leaks at high throttle (high pressure). Or did you use that hose on yours? Or was it new?
And yeah mate that would be great if I could borrow them to see if they are at fault. Want me to collect? Or can you post them?
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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hose is more than up to the job. its genuine samco vaccum hose, used it on mine with no probs.
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corsa_godfather
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Registered: 6th May 03
Location: Greenock,Scotland
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have u tried the 'paper clip' test to seee if any sensors show up faulty?
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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Yeah narrowed it down to what it is today fellas. It's my fuel pumpo wiring. The fuel pump is currently going through the X12XE purple fuel pump relay found behind the glovebox, and also through the new purple fuel pump realy on the X16XE loom. Found that out today driving dead early with no music on... everytime the throttle began to choke a "click" came from behind the glovebox, and when throttle response was gained again with another "click". Kept doing it... on-off-on-off,etc. Terrible to drive. Took the relays out, put a 9V battery accross them both to make sure they were working and mulitmetered them and running went back to normal.
Until tonight. Playing up again. So did the same. Took them out and put a 9V battery accross them, back in and running OK again. Am thinking I MAY have an earth problem. At the moment my engine loom to chassis earths are on my strutbrace. MAY be that.
But really the fuel pump needs to be running through one fuel pump ideally. And not on a switched live like I have it at the moment going through the two relays as well.
Also, the engine is REALLY overfuelling. Drinking it badly and a strong whiff of fumes in the cockpit. Not SURE what is causing this though. Think this could be linked to the fuel pump problem? Or more likely be a dodgy lambda or coolant temp sensor which is leading it to overfuel. Is overfuelling badly though.
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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u2u sent
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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Oh yeah, also can't do the paperclip test as my ECU diagnostics port isn't wired up yet as far as I know. The wire colours didn't match. So a bit lost on that one. lol 
Cheers Dave!
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scottc1088
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Registered: 7th Mar 05
Location: Chesterfield Drives: Corsa Gsi, Cbr600
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is the timing set up properly?
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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Yeah had a full rebuild. Don't need vernier pulleys with the GM reprofiled Piper cams either. Just a plug and play upgrade.
Am sure it's more electrical maybe. But timing COULD be an issue, but doubt it seen as though its' been rebuilt just before being dropped into my motor.
Going to give it a go at sorting out the fuel pump wiring tomorrow, see if that sorts out the overfuelling. If not then will try the lambda and coolant temp sensors. If not that then am lost for options, and may be the timing. What are the symptoms of the timing beig out?
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Siberia
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Registered: 9th Oct 03
Location: Leprechaun Land Drives : Zafira GSI
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is the airbox a 16v or an 8v airbox? is it drilled?
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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The airbox is a 16V airbox, drilled and has a K&N panel filter in it. I checked to make sure that it wasn't a case of it not getting enough air bu removing the airbox and fitting a stocking over the inlet pipe, if anything this made it worse. So is definitely the fuelling somewhere down the line.
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Siberia
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Registered: 9th Oct 03
Location: Leprechaun Land Drives : Zafira GSI
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strange... i have a c16xe that is doing the same so i tryed a tigra 1.4 airbox on it that wasent drilled... and it completely solved the problem...
made the car slower though so went back to the drilled airbox...
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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Yeah it's not the airflow on mine. It's the fuelling in terms of the electrical wiring. Going to give it a go today to try to solve it.
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Rileysport
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Registered: 18th Jun 04
Location: West Yorkshire
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quote:
Originally posted by Siberia
strange... i have a c16xe that is doing the same so i tryed a tigra 1.4 airbox on it that wasent drilled... and it completely solved the problem...
made the car slower though so went back to the drilled airbox...
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Tiger_kpt
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Registered: 2nd Apr 05
Location: Retford, Nottinghamshire
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Sorted it lads. Was the fact that the fuel pump was going through two fuel pump relays. The old X12XE one and the new X16XE one. No stench of fuel or overfuelling evident either. Will see how it goes over the next few days, but for now it's running like a dream. Oh, and my Splitfire spark plugs were black (carbon'd up) so guess it was running rich. Better that than lean I guess and a melted set of pistons.
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