RV8 3.9 EFI MAF Trouble

[georgeb]

If you haven't already, make sure the TPS and IAC valve are clean. they also get gunked up over time and can cause interesting running issues. But yes, an upstream air leak will give the problem you have described.

[frosty]

Right, just tried starting the engine after trying to seal the plenum better last night and it does run a little better. It starts and idles for a few seconds and then cuts out. If I try and Rev it it cuts out so I'm gonna guess it's the fuel system being the cause of the issue!!!

Need to look at getting under it and trying to tidy it up a bit. Might be drawing air in between filter and pump!!

[deaddave72]

don't forget to make sure that the fuel pressure reg is operating and that the fuel rail is air free

[frosty]

Been a while since I updated this. Still not running on the MAF properly but think I've found one major suspect!! The fuel pipe that runs from the pump and filters under the car to the engine bay has a soldered fitting at the engine bay end. This was connected to a flexy hose to the inlet on the engine. It's been on the car for as long as I can remember so I thought as it's one of the only parts I havent changed I'd have a look at it!

So I lifted it up slightly to see if I could see if the pipe connection was leaking at all and the soldered joint disconnected from the pipe! On closer inspection the fitting was VERY badly soldered on and on one edge had less than a mm of solder!!! So if that had come off whilst the engine and pump were running that would definately have been engine fire number 2!!

Picking up some new hoses and fittings tonight so will try and get those fitted ASAP. Might try and do a test setup with the pump going from a jerry can at the side of the car to see if that works!! Will know where the issue lies if it does!!

[frosty]

Ok so another update on my 'lovely' V8 that refuses to run properly for me.

Tried it running straight from a gerry can to the inlet this time and still runs the same. Changed the little vacuum hose on the return valve as that looked a bit iffy, but still the same. Now it's Bluming freezing it's running even worse!!

Beginning to give up on the whole thing!!! Might look at a few other little bits on the car instead and re-address the engine issue in the new year!!

If anyone with knowledge of these engines fancies a trip to the lovely town of Stafford in the new year, please feel free to come and help as I think I'm running round in circles, running out of patience and probably missing something really obvious!!!

[task]

Hey,

so, a few things to try;

Firstly download the RAVE manual and go through the diagnostics for the 14CUX in there step by step, these can be mostly done with a multimeter.

Do you have a resistor on the cable going to earth to tell the ECU you're running manual not auto?

Have a look at the roverguage software, you'll need to make up a cable, but it allows you to interrogate the ECU should you feel the need. Failing that my friend has autologic and could plug it in but not sure what you'd gain...

Stafford is a trek from me but if the weather is good in the new year I could be persuaded to take the MGB or the CSK for a run

[SamR380]

Oct 24, 2014 22:45:32 GMT frosty said:

Oct 24, 2014 19:05:04 GMT deaddave72 said:

Hmm... have these two pipes been plugged imgur.com/WoP0AzH or dealt with accordingly ?

Sorry just seen this. The vacuum is now connected to the brake servo as mentioned by Gavin and I've just removed the preheater. The larger pipe from the throttle body goes to the breathers on the rockers from what I can find online which at the min they don't but didn't think this would cause too much of an issue as I thought it was just a breather?!? Is that not true? If so I might try and get some breather tube tmw and hook that up!!

Did you fit the breather pipe or block it at the plenum end?

Either would be ok to get it running. If you fitted the breather pipe make sure the rocker cover gaskets seal and the oil filler cap is tight enough, the engine needs to be airtight for the breather to work. If it isn't airtight the breather pipe will suck air in like any other air leak. I found this when I forgot to re-fit my oil filler cap once!

Keep at it, you don't sound far away

[frosty]

Nov 26, 2014 14:33:02 GMT task said:

Hey,

so, a few things to try;

Firstly download the RAVE manual and go through the diagnostics for the 14CUX in there step by step, these can be mostly done with a multimeter.

Do you have a resistor on the cable going to earth to tell the ECU you're running manual not auto?

Have a look at the roverguage software, you'll need to make up a cable, but it allows you to interrogate the ECU should you feel the need. Failing that my friend has autologic and could plug it in but not sure what you'd gain...

Stafford is a trek from me but if the weather is good in the new year I could be persuaded to take the MGB or the CSK for a run

Cheers for the advice. Gonna get the multi meter out and have a look. Downloaded a manual today for the fuel injection system so will try and follow through that!

Even if I do sort it out ur still welcome to come down if there's a good day of weather!! Would be great to see one of ur motors, especially ur MG.

Cheers for the help!

[frosty]

Nov 26, 2014 17:41:09 GMT SamR380 said:

Oct 24, 2014 22:45:32 GMT frosty said:

Sorry just seen this. The vacuum is now connected to the brake servo as mentioned by Gavin and I've just removed the preheater. The larger pipe from the throttle body goes to the breathers on the rockers from what I can find online which at the min they don't but didn't think this would cause too much of an issue as I thought it was just a breather?!? Is that not true? If so I might try and get some breather tube tmw and hook that up!!

Did you fit the breather pipe or block it at the plenum end?

Either would be ok to get it running. If you fitted the breather pipe make sure the rocker cover gaskets seal and the oil filler cap is tight enough, the engine needs to be airtight for the breather to work. If it isn't airtight the breather pipe will suck air in like any other air leak. I found this when I forgot to re-fit my oil filler cap once!

Keep at it, you don't sound far away

Haven't actually done anything with the breather. Will try blanking it off and see what happens!!!

Cheers. Fingers crossed!! Will keep everyone posted!

[SamR380]

If there's no pipe it needs to be blocked at the plenum/throttle body end, just wanted to be clear

[frosty]

Cool. Will get that sorted and try it!

Cheers again!!!

[SamR380]

I should probably be extra clear, connecting the breather properly would be best. Sealing off the port at the plenum will hopefully get you away for now, or at least eliminate another possibility.

[frosty]

Ok so it's the Throttle potentiometer that is foobarred so if anyone knows of a spare one going for sale please let me know!!