New Injector Replaced - EGR Question

[gmenor]

Just replaced my injectors with OEM injectors. It wasn't the injectors that cause me hard ache it was the return lines. Any how for anyone interested, Sears has a 3/8" and 1/2" hex head adaptor that fits into the socket so you can use a wrench on it. It is in the impact socket section - real help. My observayion driving back from Fayetteville the EGT ran 100 degrees higher than normal -(400 degrees), is this expected? Boost was around 4lbs (1LB increase). No new increase of extreme power. How do I test the EGR system to make sure it is running fine? I feel it still lacks power. Pre-thanks for any input.

[john8662]

Whats the vehicle?

if its your 1995 suburban, then you don't have an EGR, they didn't make an EGR version of the 6.5 in a suburban weather 1/2 ton or 3/4 ton. Don't know about the injectors though.

How many miles were on the originals?

Did you replace them with hi-pop versions are stock replacements or rebuilds?

If you had a lot of miles on the old injectors and you just put in the new injectors that are properly atomizing the fuel then I would say an increased EGT would be correct as you are getting a hotter and more complete burn. Since you have gauges, you can check to see the boost and everything is as it was before.

[gmenor]

Well I am glad that you gave me the tidbit of information - mechanic at the dealership lead me to believe that it was a EGR problem. I replaced the injectors with new OEM stock. I don't know if the ones I replaced were the originals (I bought the Suburban used). The sure came out hard. As for boost it is .5lb to 1lb more than usual and EGT is 100 degrees hotter. The beast used to have some incredible power but it seems to have lost it's edge. Planning on replacing the exhaust later this year. Just wondering what happen to power I once enjoyed. When I first got it the engine was blowing oil onto the firewall. After closer inspection, I noticed that the original owner had CUT the intake manifold gasket (about 2 inches wide). I am not really sure if replacing the gasket would decrease power. I read somewhere back about removing a gasket from the airflow sensor would have the same effect. Could be off track.

[TurboDiverArt]

Regardless of Injectors or not. I'd think that if you are running a pound more boost then you are going to produce high EGT's. More boost, more air, more air, more fuel, more heat.

As to why new injectors produce more boost, I haven't a clue. As another poster above mentioned, if the fuel is atomizing better you'll produce a more efficient burn which could increase heat. More heat could produce more boost. I think I'm running myself in circles so I'll just stop now before my head begins to hurt.

Art.

[rjschoolcraft]

My experience with the 6.5...

More boost means cooler egt... to a point. It seems to me that the higher boost overcomes inherent pumping inefficiencies in the engine and makes the overall volumetric efficiency higher.

[gmenor]

TurboDiverArt, ronniejoe,
Thanks for the crash course on boost/EGT. The beast still runs like a brick on wheels during acceleration. Am I missing something or over looking something to have it run like pig? It is generally a stock engine with 169k, added the dual idler gears, FSD Cooler and high capacity water pump. I have replaced the ECM, vacumn pump, harmonic balancer, unrestricted the airflow going into the airbox. Turbo seems fine - what am I missing?

[JohnC]

A WAG:

Higher EGTs generally mean you're burning more fuel. Burning more fuel means there's more heat energy in the exhaust (hence higher EGTs) and that means the turbo has more energy to convert to boost. All this fits your discription. Problem is, if you burn more fuel you should go faster. You didn't mention that you're going faster, so something else must be at work.

Let's presume that you're burning more fuel to produce the same power, or, in otherwords, have adversely affected the efficiency of the engine. One cause could be that the new injectors require more pressure to open, and thus fire later than the old ones did. This reduces the advance and could negatively affect power. Or, the pump could be tired and unable to open the injectors in a timely fashion, also resulting in delayed injection.

YMMV,

[gmenor]

JohnC,
Wouldn't I get a DTC 38? I am not showing any codes. It is going to get the timing checked tomorrow and the once over. Hopefully it will shed some light on why the beast moves like a brick. Don't get me wrong, it will move out if I punch it. I am really don't want or like to push the RPM's past 2400 unless I have to. Problem is going up hills it loses a lot of power. I wouldn't attempt to pass wheel chair.

[gmenor]

I got it timed, and it has restored some of the power lost. The injector pump was not tighten down enough and over time it moved. But still where did the rest of the power go to?

[Barry Nave]

Got it timed to what? As in the off set learn TDC vaule

[gmenor]

Set to -1.95 TDC. Have to admit smoother and quieter and little improved power.