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Discussion Starter · #1 ·
Hi all. I've put a c20xe into my corsa b. It was backfiring but i found a air leak so fixed it. Its still running lumpy and will hold back from 0-5000 revs and then go im thinking MAF sensor? Any ideas please? Cheers in advance!
 

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IDLE CONTROL FKIN VALVE! It's pissed me off soo much recently.

Right, Take a picture of your bay, make sure all the pipes are connected properly, ideally with jubilee clips check these places:

Throttle body Vacuum pipes,
Vacuum pipes from the FPR
Pipes from the Rocker cover to the throttle body
Pipe coming off your brake servo pipe if you have it, should be a small vacuum pipe - block it off.
spray WD40 around areas that you may suspect and the engine note should change.

Make sure your throttle cable is correctly installed and no stress on the cable, should be slightly slack.

When it revs to about 5K, does it stay there? Squeeze the Pipe coming from your powercap to the IDle control valve, if revs drop then its the ICV most likely. Take ICV out, spray the hell out of it with Carb cleaner and a wiff of wd40, inspect inside it, clean it to a mirror finish.

Can you upload a video of it? Does it rev up then drop, rev up then drop cycle?

I had similar issues and took me a while to fix.
 

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Discussion Starter · #3 ·
I dont think its the ICV mate. It idles about 950 rpm so spot on. Its flat when you put your foot right down. Sluggish through the revs but when you get past 5000 it goes. I will test for leaks later but im still thinking MAF sensor. Cheers.
 

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Ahh I see.

Have you tried running it without the maf plugged in? If it runs better then yes, it would be your culprit most likely.

I have Maf available for the early and late one. Late maf has been tested and works. So if you're after one let me know :)
 

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I dont think its the ICV mate. It idles about 950 rpm so spot on. Its flat when you put your foot right down. Sluggish through the revs but when you get past 5000 it goes. I will test for leaks later but im still thinking MAF sensor. Cheers.
Those symptoms sound very much like MAF problems to me bud. Unplug it and go for a drive, if it runs a bit better(all be it in limp mode) then it's defo the problem, it should run fairly smooth but just be down on power with it unplugged. If you unplug it and its still all the same then it isn't the MAF
 

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Discussion Starter · #6 ·
I will try that later mate. I did unplug it yesterday and the engine note changed but i only let it idle but i did not drive it. I will have a go tonight. Can an air leak cause all this?


I will let you no if i want it mate. Is it a bosch MAF?
 

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I will try that later mate. I did unplug it yesterday and the engine note changed but i only let it idle but i did not drive it. I will have a go tonight. Can an air leak cause all this?

I will let you no if i want it mate. Is it a bosch MAF?
Yup, original Bosche genuine xe one.

Regarding the air leak, Hard to say as if it's an air leak it will usually affect it no matter what revs but as yours is idling fine I would go with maf.
When I had air leaks I took the maf out and it went back to idle at around 850 rough-950. Even with the air leaks but exhaust was popping as it was pulling in too much air and not enough fuel for the mixture. As maf wasn't plugged in - it couldn't calculate the mixture.

Anyway, do the maf unplug then drive thing and see what happens. If you buy my Maf and it stays the same I will give you a refund providing you pay for postage to have it returned. Will give you more security in buying it. :)
 

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Discussion Starter · #8 ·
Sounds good mate i will let you no when i get home from work. Its funny you say that because mine was popping a lot. Fixed the air leak it turned out i didnt fasten the jubilee clip on my eco tec pipe. When i fastened this the popping stopped but its still flat. Im using a 1.4 16v sport fuel pump. Is this suitable for the job? Maybe im not getting enough fuel?
 

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Fuel pump is fineZ

I'd do what dave suggests above, then check condition of plugs and leads.
 

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Discussion Starter · #10 ·
Unplugged the MAF tonight went to go for a drive and it struggled to move and bogged down when i pressed the pedal so i dont think its that. Its also getting very hot and fan is not kicking in. Ive been reading and now i am thinking coolant temp sensor. When i started it this evening engine was dead cold and i gave it a good rev and it sounded healthy with no splutters but it soon warmed up and started running lumpy again. So im thinking CTS? I have also heard these are a common fault. Cheers.
 

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CTS is a good shout then. Usually effects hot starts more than cold ones, I suggested leads as sounded like a misfire, and it sounds like you were.

acts aid so cheap
And can improve mpg too! Defiantly worth changing eitherway
 

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Discussion Starter · #12 ·
It has'nt missfired since i done the jubilee clip up on the top hat to the filter so i take it there was too much air getting in and messed the hole fuel/air mixture up. But i will change plugs and leads as its worth doing. I will try and get a CTS tomorrow. Do you think it could cause the engine to run lumpy and lack of power? I suppose it can effect air temp sensor etc?
 

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Yes.. Air/fuel ratio would be wrong
 

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Just bought one from Auto vaux other day. £11 odd. I have some autodata info regarding the CTS and the resistance figures the sensor should provide at certain temps etc. I will upload here when I go home.
 

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Discussion Starter · #15 ·
The coolant temp sensor has had no effect on my engine what so ever. Its idling lumpy now so im going to replace ICV and now my water pipes are balooning up when it reaches about 95°c and the fan is not kicking in and i have no idea now. I have changed my rad to a tigra 1.6 short double core rad and fan. The fan has been tested and works just not kucking in. Im fed up now. Any ideas guys?
 

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More than one issue here..


Have you checked plugs and leads?


Which water pipes are ballooning?
 

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Discussion Starter · #17 ·
Yes mate thery are all good no splits in the leads and the plugs look good. And its the short pipe from the front of the block to the rad and long thick pipe from the rad to the plastic main pipe attatched to the block.
 

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Did you remove any air when filling coolant?


Was it a new rad? Did this happen before this rad?
 

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Discussion Starter · #19 ·
I left the lid off the expansion tank and let it run untill it got to 92°c and released the air. The engine came with the rad looks like a 1.2 8v one but we had the car running first time and we didnt recognise any weird idling issues but the rad was leaking so i didnt really look at pipes. Could this new rad cause all this? I have flushed it through.
 

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That's not how to bleed the system.

You need to leave heatig on full
Blast to open up Heater matrix too, whilst filling up slowly
 
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