NH 4D56T Cold Start Issue

[Quinno]

My Paj has rough idle and white smoke at cold start only. This started immediately after a rebuild of the fuel pump and injectors at 240K. It was incredible to see. So far compression test OK (all 210-240), glow plugs and relays OK, valve stem seals and valve clearence OK, engine mounts OK, starter motor OK, battery of course OK, PCV in good order, these vehicles don't have an EGR, fuel filters and fuel delivery OK, turbo and turbo seals all good, exhaust and intake manifolds and gaskets OK. I convinced the workshop to do a second rebuild under warranty. Problem still persists albeit not as bad as before. Dyno test 3 weeks later reveals that it has lost 17Hp after the 2nd rebuild. When I go back to the first rebuild the Dyno tests also shown a 17Hp drop after a few weeks.

Anyone got any ideas?

[liam]

hi who did you get to do the rebuild rough idle could be just that the isc (stepper motor)
needs adjusting as for white smoke it could have the wrong valve stem seals in it
have had this happen at work sent head off to be machined and rebuilt put it all together
and not long after that it started to blow smoke turned out that they put the wrong
valve stem seals in this is 1 opption that can let oil in the cylinder to burn and blow smoke
hope this helps some

[Matatak]

White smoke at startup could be the glowplugs not being hot enough, as its usually due to low heat in the combustion chambers. Interesting that it only started after having the Injectors and Pump done though.

White smoke will be nothing to do wiht the Valve stem seals Liam, that would be blue smoke.

It sounds liek you should be getting the Timing and Fuel Mixture checked on the Injection pump really.

[Quinno]

Thanks guys. the valve stem seals weren't changed so they are definitely the right ones. They were only checked and the clearence checked. I have just organised to get another fuel injection specialist to look at it in Perth. I question the ability of the first workshop (not in Perth).

[Set0]

i have been told that the head bolt need to be re-tourqued for the first 6months after putting a new head gasket in. As the gasket they use has to compensate for a steel block and an alloy head, so there will be some shrinkage. Which may allow some leeking. Not 100% sure, but its something you could investigate. Re-tourquing the head is easier than another rebuild

[Blu Ballz]

When they did the fip did they put the right plungers in? It sounds like it doesn't have a cold start device to retard injection to build temp and pressure up. But i would be looking at glow plugs, right injectors?

[Pedro95]

My Paj has rough idle and white smoke at cold start only. This started immediately after a rebuild of the fuel pump and injectors at 240K. It was incredible to see. So far compression test OK (all 210-240), glow plugs and relays OK, valve stem seals and valve clearence OK, engine mounts OK, starter motor OK, battery of course OK, PCV in good order, these vehicles don't have an EGR, fuel filters and fuel delivery OK, turbo and turbo seals all good, exhaust and intake manifolds and gaskets OK. I convinced the workshop to do a second rebuild under warranty. Problem still persists albeit not as bad as before. Dyno test 3 weeks later reveals that it has lost 17Hp after the 2nd rebuild. When I go back to the first rebuild the Dyno tests also shown a 17Hp drop after a few weeks.

Anyone got any ideas?

Hello Quinno

This sounds just like my problem with NJ last year. Needed to have fuel pump reconditioned. There was significant deterioration in rubber seals due to changes in diesel fuel refining standards. Cost me $1500 for rebuild and $500 labour. Had tried injectors, glow plugs, one-way valve on fuel line, new filters, switching to BP fuel. Nothing helped but problem kept worsening. Runs a treat ever since.

You need to go to specialist diesel mechanic!

Good luck
Pedro

[Quinno]

Thanks for the feedback guys. Set0 - the head gasket wasn't tampered with. Only the fuel injection pump. Blu Ballz - glow plugs ruled out as the issue. Checked the entire system on 3 occasions. Right injectors? not a bad question. Pedro95 - unfortunately in my case the rebuild is what stuffed it. Probably didn't need it in the first place. If I had my time again I would have only done the injectors. Spot on with your suggestion that I go to a 'specialist'. Not a bunch of idiots in Bunbury that think they know fuel injection.

[ziggy]

My injection pump has developed a external leak, just on the engine side somewhere.

Would an exchange pump from someone like this

http://cgi.ebay.com.au/MITSUBISHI-4D56-4D56T-DIESEL-FUEL-INJECTOR-PUMP_W0QQitemZ260450623031QQcmdZViewItemQQptZAU_Car_Parts_Accessories?hash=item3ca4111e37&_trksid=p3286.c0.m14&_trkparms=65%3A1|66%3A2|39%3A1|293%3A1|294%3A50

be more economical than getting a rebuild. Since I have timing belt change coming up anyway, and would a off the shelf pump like that be tuned ok if fitted correctly timing belt wise?
PS engine is running sweet as, no extra oil in sump, but leaves puddles everywhere .

Qinno - on your issue, is the glow relay activating for long enough? If you give it more glows does it run better. Im also finding in the cold weather that more throttle is required first up , which to me points at maybe a cold idle adjustment - be it a solonoid or stepper - not sure what these pumps have on them

[dusty_nz]

Glowplugs

Mine was/is doing that as well. Pulled the injectors and got them serviced. Also checked the glowplugs.

Injectors were shot. Fitted recon ones back in andbetter but still white smoke. To me it feels like glowplugs as once the engine starts to warm it smooths out.

Is it possible the glowplug timer is to short? Eg do the glowplugs go out after the lights on the dash has gone off?

I noted heaps more power and better idling once the injectors were serviced.

[Quinno]

ziggy - the glow plug relay stays on for plenty of time. Giving it extra time or turning it off and then glowing a second time doesn't help. If I give it more on the throttle control it does help sometimes but it certainly throws in several noticeable misfires. I'm not too sure about the cold idle adjustment either.

[Quinno]

Dusty - yeh it gets better as the engine warms up. A bit of white smoke doesn't bother me, it's the misfiring at cold start and lack of power that's worrying. As mentioned the vehicle lost 17Hp between the time of rebuild and Dyno 3 weeks later. It all comes back to getting it done properly, not by cowboys in Bunbury.

[Blu Ballz]

My injection pump has developed a external leak, just on the engine side somewhere.

Would an exchange pump from someone like this

http://cgi.ebay.com.au/MITSUBISHI-4D56-4D56T-DIESEL-FUEL-INJECTOR-PUMP_W0QQitemZ260450623031QQcmdZViewItemQQptZAU_Car_Parts_Accessories?hash=item3ca4111e37&_trksid=p3286.c0.m14&_trkparms=65%3A1|66%3A2|39%3A1|293%3A1|294%3A50

be more economical than getting a rebuild. Since I have timing belt change coming up anyway, and would a off the shelf pump like that be tuned ok if fitted correctly timing belt wise?
PS engine is running sweet as, no extra oil in sump, but leaves puddles everywhere .

Qinno - on your issue, is the glow relay activating for long enough? If you give it more glows does it run better. Im also finding in the cold weather that more throttle is required first up , which to me points at maybe a cold idle adjustment - be it a solonoid or stepper - not sure what these pumps have on them

Putting a recon pump on would be find as long as they are "timed" by useof a micrometer.

[dusty_nz]

missing

Well when mine is cold (10 degree morning) it misses and complains for about 10-20 seconds and then it will smooth out and idle happily at around 600rpm and when warms idles at around 900rpm.

Power seems fine but I am always tender with it when cold until the gauge starts to move.

Not sure if I should worry about the smoke on startup. Its more a really light grey than white. White can indicate water.

[Blu Ballz]

White smoke is more fuel coming through the system and therefore you dot have enough air for complete combustion. Have you checked your air filter or to see if the are any restrictions of flow.

It is quite normal for a diesel to have smoke on start up.

if it is not excessive and only happens on start up i would not be worrying about it atm