Detroit DDEC-IV EGTs

Is the probe on the hot side of the turbo or cold side? That makes all the difference on what the numbers will be.

 

You might want to check if the intake manifold gaskets are leaking. Lots of places check for leaks by plugging one side of the CAC and appling pressure to the other side. I'd get that done because high heat like you have is usually a loss of boost pressure or some kind of reduced air flow. After that make sure the gauge is working right.

 

retarded timing is doing it too, advance the timing where it should be with bully dog or the like will help it cool off

 

Is it hard to spool up? Mine become a dog one day, with EGT similar to yours out of the blue. I had the CAC rebuilt, new intake gasket, and on and on for four days from the parts changing morons at Neel Coble until they gave up. Brought it to the Orlando Detroit dealer, and those morons told me I needed everything from a bottom end rebuild to 6 new injectors. I went to the manager and told him I'd spring for the injectors, but if it didn't fix it, I wasn't paying and lets draw up the agreement now. Needless to say, more tests were ordered, and the monkeys finally pulled off the exhaust side pipe to look at the turbo to discover it was missing 80% of the fins. A piece of debris came off the turbo housing and took out the impeller. It took 5 days for Detroit to figure that out, and Neely Coble gave up. I thought that was the first thing they checked as high egt are usually a sign of not enough air. 2000 Western Star w 12.7 DDECIV

Check your air filters, then both sides of turbo, then have CAC pressure tested, then intake gasket, make sure the hose from intake to air compressor isn't ruptured. One of these should fix your problem. Change you fuel filters for good measure too.

 

Normal temps for todays engines, forget the EGT gauge if your engine is stock. Do not use manual fan switch, it will run too cold coolant temps and you have the risk of scoring the pistons/liners.

 

Sorry, reviving a zombie thread here. For those in a similar situation, going with a PP or Bully Dog ported and coated exhaust manifold and getting rid of the wastegated DDEC IV turbo and replacing with a Borg Warner 171702 turbo (ball park $700, no core charge) will easily drop those EGT's well over 200F. No more center section cracking, better response, and usually better mpg as a bonus. You could leave the wastegated turbo on, but why put a nozzle on a garden hose? It is the small housing of the wastegated turbo that is choking up the exhaust and causing those high EGT's. One has to get that exhaust flowing and out of there. The wastegate turbo is fine for P&D local running, but it is not ideal for super slab and hill climbing. High flow, straight thru mufflers like the Walker Megaflow (ball park $115) will help also as will a good turbo blanket like one from PTP ($160). The Pitts Power one is identical but twice the cost of one from PTP Turbo Blankets.

No need to settle for high EGT's with a DDEC IV. The stock EOM stuff is like sticking a corncob up your tail pipe.

 

No need to buy manifold if not cracked ! The ddec IV manifold flows way past anything you want to do ! Now you can't just put a non waste gated turbo on an ddec IV without deleting the VGT out of the program ! I put a turbo from Mr. Haney on mine and PDI deleted the egr and vgt turbo out of the program ! Runs great and took all the egr parts off the engine and chunked them !

 

The DDEC IV did not have a VGT turbo. That began with the DDEC V. The DDEC IV is a waste gate turbo, there is no coding in the ECM involved. The waste gate opens or closes based on PSI of the fresh air side. The stock manifold will work, but the wastegate turbo is still the main choke point. Like I stated, it is like putting a nozzle on a garden hose. It slows the flow of the exhaust out of the manifold due to the small housing, which in turn makes the engine work harder to expel exhaust and higher EGT's are a result. Also, it is the main reason that the center section of DDEC IV engine exhaust manifolds are prone to cracking. A non waste gate turbo is a simple plug and play bolt on proposition with no changes to ECM code on the DDEC IV. The VGT came on board with EGR DDEC V. I will concede, that there were a limited number of DDEC IV engines that had EGR, but it was very limited and most DDEC IV engines do not. I just purchased a 2013 FL Columbia glider with a factory remanned DDEC IV 500 hp Series 60..... no EGR in sight and it had a wastegated turbo on it that promptly got replaced with a BW 171702 non-wastegated turbo. The wastegated turbo is easy to spot..... small exhaust housing and a blue hose attached to a wastegate valve.

A wastegate turbo is basically a "one size fits all" solution by Detroit. It gives a little faster spool up, which is better for city, P&D type of work. But for open road working, it creates a bottleneck. A properly sized non-wastegate turbo will spool fine and provide more boost and decrease EGT's on a truck that is doing OTR or line haul. The Borg Warner 171702 (470-500 hp) or the 171701 (435 -470 hp) non-wastegate turbos are specifically sized to give max performance, lower back pressure, and good spool up. I also mentioned a ported and coated manifold, in that it will flow the exhaust far and away better than a stock manifold, and will really bring out the best of a non-wastegate turbo. A ported and coated manifold usually will flow up to 200 CFM more over stock. Combined, 200F - 250F drop in EGT's is normal in a hard pull situation. If you get the chance, just compare, side by side a stock wastegated turbo with a non-wastegated one. It will make you wonder how exhaust gets thru that little wastegated turbo housing. The non-wastegated ones are typically a T6 housing and substantially larger than the stock wastegated one.

Feel free to check anything I state with most any diesel performance specialty shop. Area Diesel, Rochester Turbo, Pitts Power, Serious 60, Full Tilt, or any other similar shop. It is common knowledge and readily available from many sources. I would like to take credit for the information, but many before me figured this out. I am just riding on their expertise, which is real world proven.

The nice thing is the cost. A typical wastegated stock turbo is $1300-$1400 with a core charge. A non-wastegated Borg Warner turbo can be had for $700 or less and NO CORE CHARGE! I got mine recently for $685, no sales tax, and free shipping.