High EGT's

[cm1hedge]

I was climbing a 14 mile, 6% grade last Friday. I was doing about 50mph following someone else. I was carrying around 750 lbs. My EGT's were hovering around 1050 and could easily reach 1200+ if I pushed it a little bit. The best boost pressure I have seen have been around 8psi. Downshifting did not appear to affect EGT's. My probe is located about 1 1/2" from the left exhaust manifold. I performed a cylinder contribution test, and it showed #5 injector was weak.

1. Are these numbers high?
2. Will a weak injector cause high EGT's?
3. What else could cause my problem?

 

[rebel_horseman]

Well looking from your sig, you're still choked down with the factory muffler. that may be a contributing factor since the turbo can't spool very well. Did you try switching off your 10K since I've heard that this mod can cause the high EGTs.

The numbers sound a bit high but you're pulling a long steep grade so some temps are to be expected. The boost number sounds really low though. You may want to go through and check the boot from the turbo to the intake...sounds like you are losing boost somehow.

 

[Mike]

I was climbing a 14 mile, 6% grade last Friday. I was doing about 50mph following someone else. I was carrying around 750 lbs. My EGT's were hovering around 1050 and could easily reach 1200+ if I pushed it a little bit. The best boost pressure I have seen have been around 8psi. Downshifting did not appear to affect EGT's. My probe is located about 1 1/2" from the left exhaust manifold. I performed a cylinder contribution test, and it showed #5 injector was weak.

1. Are these numbers high?
2. Will a weak injector cause high EGT's?
3. What else could cause my problem?

I'll take a stab at this for you;

1. No, those numbers arent too high from an engine safety stand point but are a bit high for what you were asking of the pickup at that time.
2. Thats hard to say without having the injector of a flow test bench to see if it is still atomizing the fuel or just dribbling it in the hole, were you seeing clouds of black/gray smoke during this pull up the grade? If not, then you probably werent exhausting raw fuel. How many miles on the injectors?
3. What kind of RPM's were you turning when pulling that grade? I know you said you down shifted and it didnt seem to help. Just curious what kind of revs you were seeing. These PSD's like to stay north of 2200 when lugging a load but.....................750 lbs in no kind of load, thats where my 95 F-350 started to ride nice actually. Also noticed that the cat is gone but you still have the stock turbo downpipe? That guy is probably your culprit. Finish your exhaust modifications and see if it helps.

 

[rebel_horseman]

Yeah that's what I was trying to get at. Methinks opening up the exhaust would go a long way in dropping EGTs and giving you more peak boost. This is especially true on the OBS with that retarded oval down pipe.

 

[cm1hedge]

I am running a Bully Dog 3" down pipe. Still stock muffler. The injectors have 217,000 miles on them. Thank you for all the help.

 

[rebel_horseman]

The 3" is part of the problem since that's your choke point. The rest of the exhaust is 3.5". The **** is also a choke point. Those 2 alone should help quite a bit. for perspective, my 160hp 1st Gen Cummins has a 3" down pipe. While the injectors aren't terribly old, they may benefit from some R&R work.

Luck with it.

 

[Mike]

On the OBS the 3" DP is about the best you can do without major mods, so we can eliminate that but 215K on a set of injectors is plenty. But before we go and jerk your injectors out you need to be sure you dont have air induction issues..... boost leaks at the intakes, clogged air filter, dusted compressor wheel, blown up pipe donuts etc etc.

 

[ward cleaver]

Get the aftermarket downpipe, at least a 4' exhaust system, kitty delete pipe, and an exhaust backpressure valve eliminator. this will cool that sucker down. if not still not enough get an intercooler.

 

[Mike]

I am running a Bully Dog 3" down pipe. Still stock muffler. The injectors have 217,000 miles on them. Thank you for all the help.

How about the smoke output on the long grade?

How about those RPMs?

How about the results with the 10K switched off?

 

[Mike]

Get the aftermarket downpipe, at least a 4' exhaust system, kitty delete pipe, and an exhaust backpressure valve eliminator. this will cool that sucker down. if not still not enough get an intercooler.

He's got the DP and the cat is removed, Ive seen trucks make 400 hp through the stock 3.5" pipe, I truly dont believe that his exhaust is his issue unless his muffler is plugged or the pipe is crushed somewhere along its exit path. The only modifications to the injection circuit is the 10K mod so I dont think he is overfueling either, The EBPV could be partially closed, wiring it open would be a good troubleshooting aid at this point. An intercooler will only make his 8 psi of boost worse yet.

 

[rebel_horseman]

To me it just sounds like he's losing boost somehow. Low power, high EGTs, and low boost. Either the turbo is toast, the EBPV is stuck, or the hoses are pin-holed or otherwise FUBARed.

 

[69dieselfreak]

ok what is normal boost pulling a hill in a stock powerstroke
what are normal egt for a stock power stroke
does anybody know because this might help in diagnosing the problem

 

[Mike]

Normal maximum boost for a stock OBS PSD pulling a hill with a load would be around 17 psi. Normal EGT's under those same conditions would be somewhere in the 1100° neighborhood is my best guess.

The main reasons Ford (and others) didnt put boost and EGT gauges in stock trucks is that #1) your average owner doesnt understand the gauges and they would increase dealer service visits and #2) the PCM is programmed stock from the factory to NOT put the truck or engine components in a danger situation.

 

[ward cleaver]

My truck never saw 17 psi without my TW chip (over 17 will set CEL), but the EGT's pulling my 14k lb trailer outa da desert can go over 1250 if I keep my foot in 'er. Unplug the cable at the bottom front of the turbo pedestal (EBPV). this will open the EBPV and the restriction in your pipe. Next check the rod to make sure the valve is opened all the way (rod fully extended), That's what I had to do. As for the low boost I suspect your turbo is toast or the boots are leaking. Smoke sounds like an injector issue or high blowby.

 

[Mike]

My truck never saw 17 psi without my TW chip (over 17 will set CEL),

I could get 17 psi on my 95, not in stock form though, I had intake and exhaust mods done (no chip or programming alterations at all) and the 10K mod with FPR shim. So, on a totally stock truck 17 psi would be high, 15 psi wouldnt be though. I frequently saw 36-40 psi after the injector mods and chip installation and never set a boost CEL.

As for the low boost I suspect your turbo is toast or the boots are leaking. Smoke sounds like an injector issue or high blowby.

I agree, early on I suggested this;

215K on a set of injectors is plenty. But before we go and jerk your injectors out you need to be sure you dont have air induction issues..... boost leaks at the intakes, clogged air filter, dusted compressor wheel, blown up pipe donuts etc etc.