cfd511 Posted June 2, 2023 Share Posted June 2, 2023 I have a 2000 mack rd 688 . While driving the truck will lose all throttle response and shit down. If i feather the peddle i can get it to come back to life if i leave in gear or i can pull out of gear , turn switch off and start again and it first right up. I drove for a little while yeaterday and nothing happened . My worker was driving and running loads today and it happened . Seems to happen randomly or when gets hot. Also when the truck shuts down while your driving , a huge cloud of black smoke comes out from stack . Any ideas , im thinking maybe the ecu Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/ Share on other sites More sharing options...
Joey Mack Posted June 2, 2023 Share Posted June 2, 2023 How about loose ground wires???? ECU issues are rare.. Simple stuff is common.. Look up how to fix a 9-2 code... Mack E-Media has a bulletin.. and Myself and a handful of others have posted the procedure here on BMT... You Will be pissed when you buy an ECM, that know one knows how to 'Flash' , only to find out the engine block ground bolt was loose... Jojo Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532305 Share on other sites More sharing options...
JoeH Posted June 2, 2023 Share Posted June 2, 2023 The black smoke seems odd, but does it trigger a fault code? Does the lightning bolt dash light work? I chased a similar situation on my 2003 mr688, it wound up being the EECU fuse/circuit breaker was loose. Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532317 Share on other sites More sharing options...
Bill 88 R 688 ST Posted June 2, 2023 Share Posted June 2, 2023 We had a 2000 RD chased similar problem without black smoke issue and ended up being a loose engine ground... Check fuses/relays for corrosion/tightness, and engine grounding for corrosion/tightness before buying an ECU... 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532320 Share on other sites More sharing options...
fjh Posted June 2, 2023 Share Posted June 2, 2023 10 hours ago, JoeH said: The black smoke seems odd, but does it trigger a fault code? Does the lightning bolt dash light work? I chased a similar situation on my 2003 mr688, it wound up being the EECU fuse/circuit breaker was loose. check the air inlet system for rags bags and bird nests! Black smoke is a lack of air problem not fuel or Electrical! also I have seen where the little plastic rain cap on an MR can suck down maybe this is could be happening on the RD and cap off air to the engine check that or remove it see if the problem goes away! the other Possibility is the truck equipped with an air cutoff valve Oil PATCH truck or gas hauler ? The other thins to check for is the charge air hoses to the engine could be rotten and coming apart inside and are creating a flapper valve inside the hose where you can't see it! if any of the hoses look rotten change em! 2 Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532330 Share on other sites More sharing options...
Bill 88 R 688 ST Posted June 3, 2023 Share Posted June 3, 2023 Good call fjh, Once upon a time in my trash collecting days, I drove a MR with a Leach packer body on it, and the air intake rain cap had gotten pushed down by a branch or something, and compromised the mesh on one side, it would run like a champ all day long and lose power/black smoke and kill itself only when climbing this specific hill. pull over and it would start right up and run fine till the next climb... took a bit to catch it but it is a possibility to check in too for sure.... Was almost 25 yrs ago when I piloted that fine unit... Old age brain fog had clouded that memory... 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532366 Share on other sites More sharing options...
Bill 88 R 688 ST Posted June 3, 2023 Share Posted June 3, 2023 Problem was that under extreme suction the cap would collapse and cut off air flow to engine... 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532368 Share on other sites More sharing options...
fjh Posted June 3, 2023 Share Posted June 3, 2023 11 hours ago, Bill 88 R 688 ST said: Problem was that under extreme suction the cap would collapse and cut off air flow to engine... yup Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532384 Share on other sites More sharing options...
cfd511 Posted June 10, 2023 Author Share Posted June 10, 2023 Update , mehcanic thought the turbo inlet tube was collapsing , disconnected tub all together and truck ran well so he put a hard air inlet tub in . fast forward to today and we are stuck on the side of the road. Truck starts , idles at 900 rpm , no throttle Response and when you turn the ket off, the truck starts to shut down and when it almost shuts off it it goes back to running then tried to shit off again Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532765 Share on other sites More sharing options...
steeler Posted June 11, 2023 Share Posted June 11, 2023 Idles at 900? Sounds like the infamous 6-4 fault. Any fault codes? Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532793 Share on other sites More sharing options...
fjh Posted June 11, 2023 Share Posted June 11, 2023 pull the VECU from under the dash and check the plug to it these sometimes get water in the plug from a leaking windshield! 2 Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-532800 Share on other sites More sharing options...
Popular Post cfd511 Posted September 16, 2023 Author Popular Post Share Posted September 16, 2023 thank you all, I was the plugs under dash were dirty. 3 Quote Link to comment https://www.bigmacktrucks.com/topic/72911-mack-r-688-shuts-down-while-driving/#findComment-538880 Share on other sites More sharing options...
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