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DBGraves

99 E7 E Tech 400 missing and white smoke between 800 to 1000 rpm

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Good afternoon everyone 

i don’t post much but do read a lot of the post and learn a lot from this form. Any knowledge or comments this is my thanks in advance for taking the time. 

My 99 ETECH 400 is missing at low rpms also white smoke and raw fuel smell. This all happens between 800 and 1000-1200 rpms.

motor was rebuilt less than 16000 miles ago. I put reman injectors I have replaced all timing sensors ( front cover and bell housing) just replaced lift/supply pump this morning still the same. The motor runs fine above 1200 rpms. Between 25 to 32 psi boost. 180 degrees stays cool. Pyro is down around 300 sometimes but on a pull is around 900 degrees. 

At idle it sounds like the jakebrake is on kinda but I’ve pulled the wires off the jake housing to kill it but still sounds the same. 

Please Help. 

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In my opinion You need to remove the valve covers an look for a valve train issue a bent push tube or the like

Edited by fjh

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10 4 I will do some snooping under the valve covers to check. I’ll update soon as I can 

thanks for responding 

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Might be curious to see what temp the computer thinks the intake is seeing and whether it’s actual......

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Check your fuel supply pressure; had my 95 e7-350 make the same sound for a while, only difference was mine did it at the top end, near 1800 rpms. Took 2 sets of fuel filters to get rid of it. First set cleared it up for a few days, second set made it go away for the past year or two.

Your supply pump could be shot, not making enough pressure until it gets up a little bit in RPMs.

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Thanks Mack Technician for the comment

the CPU showed no codes But I haven’t had Mack put it on there and monitor it while it runs .what do I ask them to check ? 

 

 

 

Thanks Joe H for your comment and info. 

I just replaced the supply pump today no change in the sound or the smoke.  I haven’t pulled the valve cover yet to check valve train. I’ll keep you guys posted. 

Edited by DBGraves

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If you get as far as taking it in you place the burden of identifying the problem directly on the mechanic. If it will do it for him while plugged in he shouldn’t have a lot of trouble finding it..... including the basic instruments to check fuel pressure, aeration, etc.

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Ok I can make it do it while I’m driving it. Just have to get them in the truck. Thanks for your info Mack Technician 

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Pulled valve covers everything looks like it should. Back jakebrake housing was replaced when the engine was rebuilt. All the push rods seem to be straight. What little bit I know and i mean little. I’m leaning towards a ECU problem. Reason I say this is it did not have this problem until after the engine was built. Any other thoughts you guys?

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I’d grab a “know good” charge air temp sender from another truck and swap them out. Then take it in if no fix. 

Mack had issues with smoke stumble at low RPM. Yours should already have the fix. It was a software file or adding a 1,000 ohm resistor to the charge air temp sensor. 

Edited by Mack Technician

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10 4 sir I will give it a try and see what happens it might take a day or so to get one. 

Again thanks for your help. 

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13 hours ago, Mack Technician said:

I’d grab a “know good” charge air temp sender from another truck and swap them out. Then take it in if no fix. 

Mack had issues with smoke stumble at low RPM. Yours should already have the fix. It was a software file or adding a 1,000 ohm resistor to the charge air temp sensor. 

Yup if it is the smoke and stumble file issue I wonder why it has chosen now to show up ?kind of odd! Something else l have been thinking is maybe a broken eup spring .just odd it’s happening in the same rpm range! The smoke and stumble usually showed up at a stop light some sort of heat sink issue either inlet sensor it though! Try to pay attention to when it happens and set instances!

Edited by fjh

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I’m not sure fjh I had the motor rebuilt recently and in the bulletin that Mack put out that some one had posted on here awhile back. It talked about if major components was changed that it might do this. The problem only arrived after the motor was rebuilt. 

I can make it do it all day from 800 to 1100 rpms but long as i stay above that range it runs like a top. Every stop sign and stop light does it  and being it’s a quint axle dump truck with 23 tons it kills it  

the resistors should be in tomorrow . Witch wire do I put it in or does it matter?

 

thanks for you Guys help  

 

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Either wire, solder and shrink only. No butt connections.

I also find it strange that it decides to appear now. The sensor swap would have been my best case scenario, cheap check. If you want to try resistor be conservative about burning any bridges by cutting a bunch of wire out. You have only a little to work with at that spot.

Did it run well for a period after the rebuild, or go chronic immediately? I’m guessing it was OK for a while or this would be a warranty conversation?

 

 

Edited by Mack Technician

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If installing the resistor is a little drastic I can order the sensor first they aren’t that expensive. 

The problem was instant. The motor wasn’t rebuilt at Mack. And it took forever to get it back. It was rebuilt by the guy I bought the truck from his mechanic BIG mistake on my part. But mechanically the motor is fine. My Mack place says everything looks good. They seem to think it was a short causing the problem. Everything has been checked over and looks good. So leaves it to the CPU. I want to try everything I can at the house before I take it to Mack.

But in the bulletin it states not to have the resistor in the wire if they put the program in the CPU

ill see if I can find it again and post it on here. 

Thanks for yalls help. 

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If it were a short it will likely show up as a fault does the check engine light eliminate when the miss occurs? EUP malfunctions should show!

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Nope shows no codes at all. When the motor was rebuilt it showed 1 code for timing sensor so I replaced both of them. Since then no codes. Or light rather. 

Thanks for yalls help

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Be curious to see the cure... the air temp is a weak spot where the sensor can be inside its “legal range”, not be setting a code and has been able to produce that symptom, historically.

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I got one on the way. Should be here in the morning. I really hope it does the trick. 

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Too bad it’s a keyed sensor. Be fun to build a small break-in harness that has your resistor in-line. You could pop the 1K OHM harness in and out without cutting stuff. 

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That would be cool and easy. I put the new sensor in. No changes problem still there resistor should have came in today so I’ll put one in this evening 

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7 hours ago, Mack Technician said:

Too bad it’s a keyed sensor. Be fun to build a small break-in harness that has your resistor in-line. You could pop the 1K OHM harness in and out without cutting stuff. 

There must be a way to do this.? Give us some part #s I wanna try too. but dont wanna cut into harness.

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