Turbo response

[big61fourby]

Last week, it seemed like all of a sudden, my turbo started spooling up slower off the line. It takes more throttle input to make the boost gauge move. Not much, but enough to be noticeable. Seems like 'turbo lag', for lack of a better term.

I pulled the intake elbow off, no signs of any obstruction. Just oily as always. No in/out play in the turbo, and up/down was only SLIGHTLY more noticeable than before (engine warm). Air filter doesn't have that many miles on it, but I have not pulled the box apart to check the dirty side yet. Ran the Turbo Master in just a bit, and overall boost increased, but it still seems to lag off the line. Anything else to check, or just not worry about it?

[DmaxMaverick]

Check your fuel filter and lift pump operation. Slow fuel = slow spool. Most turbo complaints are fuel related. By the looks of your sig, you probably don't have a cat, but they will do the same thing when they get plugged up.

[big61fourby]

Interesting. Cat was gone way before I bought it, and I just changed the fuel filter & lift pump around 1500 miles ago. I usually go 10k on the fuel filter, but I'll check it anyway.

On a side note, lift pump failed Sept 2005, and I installed a lifetime warranty Carter from Orielly's (hehe, gonna get my monies worth:D ). 1 year to the week, the Carter failed, so I took it back, and got the 'we don't carry the lifetime anymore, but you can take a limited 1 year unit' (gee, wonder why), which was some off brand I've never heard of. :mad: As much as I hate the extra noise, I could instantly tell when the Carter quit pounding away, but this off brand deal--sometime I can hear it, sometimes I can't. (any way to rig up an indicator light to tell when it's actually pumping??? already have a little hole in the dash just waiting for an LED...)

[DmaxMaverick]

An LED could be rigged up, but it may not tell the whole story. The best option is a fuel pressure gage, or rig the LED to a pressure switch (idiot light).

Did you also replace the OPS (Oil Pressure Switch) with the new pump? Many times the pump is replaced, only to have the OPS fail a short time later. A better option is to install a relay to power the pump. This takes the load off the OPS, and supplies a more steady current flow to the LP. The OPS can, and often does, fail intermitently over a long period.

[big61fourby]

I actually have a new OPS, so maybe I better just change it. I haven't taken the time to install it, as mine is a late 96, with dual t-stats, updated CAD, etc, and I thought I read that they changed the circuit mid-year to take the load off the OPS, but I could be wrong.

[gmenor]

Check the vacumn also

[Hubert]

Any increase in black smoke? Or change in overall boost, max boost?

When you say turbo lag when exactly is it. The ECM drops the duty cycle of the wastegate solenoid at light throttle (maybe 2-5%) under 2000 rpm. But comes back to more wastegate closed vaccum at no throttle or senses load. I am not sure how it senses load might just depend on throttle position.

Vaccum pump health, lines, solenoid etc? Low cetane fuel?

[big61fourby]

I'm running a Turbo Master (mechanical waste gate), so forget any vacuum anything. :D I haven't seen any noticeable power drop.

It is slow when in the lower RPM ranges; it's especially noticeable when starting from a dead stop. Run the pass. window down, and I can hear it beginning to spool, but won't move the gauge as easily, and it doesn't sound as crisp as it once did.

Interesting you should mention centane, could this possibly be ULSD related? It didn't appear right after a fillup, more like the last 1/3 tank.

Air box is clean. Lift pump is pounding away, but don't have a gauge on it (how many psi???? <15?). Fuel filter was darkish, but didn't look that bad, records indicate 3k on this filter. Fuel in bowl looked good. Weak lift pump??

Starting performance (esp. cold) has also been declining. 5 easily accessible glow plugs are functioning; should probably replace the remaining three with the ones in the glove box from PO:( ). I suppose this could also be a fuel issue.

What else am I missing? Thanks...

[DmaxMaverick]

Glow plugs are only an issue at cold start. After that, they sit doing nothing until the next cold start. 3 bad plugs could cause slow starting, but no problems after that. I've been able to get started with only 2 hot plugs. Rough going and a LOT of smoke, but it ran fine after a minute. No mosquito problems that morning!

Still, your lag has to be a fueling issue. If it wasn't in such a short period, it could also be timing. Usually, timing degradation happens so slowly, you just don't notice anything drastic. The fuel pick-up sock is also a possibility. Fuel pressure should be 4-9 PSI at idle. Under full load, any pressure (even .1 PSI) will not hinder IP operation.

Weak pump? Possible. What's the condition of your return lines? If they get kinked/blocked or there's a leak, it can effect fuel delivery.

Another possiblility is an air leak. If you are sucking air between the tank and LP, you will be down on power. It doesn't take much.

The ULSD could be an issue. I haven't noticed any difference here due to the fuel (100% ULSD), but I do notice a performance drop when I don't use a cetane booster, before or after the ULSD. Perhaps, try a cetane booster. If you get your power back, then you can blame the fuel. Not comforting, but it is an answer. I usually boost +6 on the cetane. The increased mileage pays for it.

[DA BIG ONE]

Perhaps, your turbo is getting coked up at the bearing, or something has obstructed exhaust muffler/cat. I've seen mufflers come apart on the inside a somewhat block flow.

[Hubert]

Dang I read your signature looking for turbo master and missed it somehow. Otherwise would not have posted about vac stuff.

Anything else new or what was latest change when you noticed more lag?

Run a heavy dose of stanadyne performance formula for a couple of tank fulls (2-3x reg dosage). I like FPPF 8+ cetane boost along with the S.P.F. I am pretty sure either of those products you can't overdose within reason. Not always the case with addatives. One marginal quality tank of fuel might take a few good tanks to clean up effects fully. I am really not usually a brand loyalists on coolant/oil/chemicals etc but I do notice a difference in fuel addatives and highly recommend those two above.

Yeah 15 psi gauge for fuel pressure is all you need. Its a good added gauge for these trucks. My lift pump broke and I did not notice it until filter change. I thought cranking there was a very subtle difference (I dismissed with cold weather) and really there wasn't much difference in performance light daily driving. Pressure isn't everything flowrate is really it but I haven't seen a flowrate gauge.

[big61fourby]

I ran Stanadyne and then Power Service for quite a while, and am currently running the Lucas stuff, around 8 oz./tank, because it was available. Are there any national retailers that sell the FPPF product?

Been researching gauge options, but really don't like the idea of a mechanical pressure gauge in the cab. Are there any kits that include an isolator? I could mount it underhood, but that doesn't help much while driving, so I may just go with an idiot light. What do you guys use for fuel pressure gauges?

Hadn't thought of coking on the turbo bearing. Haven't ever shut it down real hot, and this seems to have appeared within several days. Any way to check that without major disassembly?

Right now, I tend to think it might be a fuel issue, but don't quite know what at the moment. Maybe injectors? Haven't noticed any unusual smoke, just a little on startup as usual...

[Hubert]

You can add 1 quart synthetic to 6-7 quarts dino oil to mildly clean engine internal and maybe help turbo bearing. One of the lucricant vendors told me this and explained it was due to the base stock and addative packages being different. I am leary of motor flushes or any miracles in a can.

I used an electric Autometer 15 psi pressure gauge. I looked around for a mechanical isolator but by the time you added that into costs it was close to the same for all electrical. There are several brands. I went with Autometer to closely match my other black face gauges.

Are injectors original? Bad fuel + worn nozzles/injectors might have compounded the problem. My truck slowly deteriorated for throttle response as it aged. It seemed a more speedier decline after 130K miles but it was still a rather slow decline. It was really apparent how bad it had gotten when I changed injectors. I changed my injectors recently at ~140K and it pepped the throttle response back up. I think if I would have replaced timing chain too it would have felt as good as when I bought the truck at 70K miles. I hope to do timing chain next summer.

Lots of the diesel vendors sell Stanadyne and FPPF mail order. I have seen FPPF at truck stops but not all varieties of their products. Try a local injection pump shop. I'll bet they carry it and stanadyne performance formula or other good addative(s). Luccas was OK for me. I did not really like Powerservice. If I mixed either of those products too heavy with fuel I'd get some ill effect. Lucas caused a studder on launch (low rpm varing load fuel metering problem) and PS increased smoke if too heavy a dose. I'd say both are good for general maintenance in proper proportions but Stanadyne is better stuff IMHO. Again ask a good local IP shop what they use. Mediocre or bad fuel is something they see a lot and I feel if they recommend something its usually pretty good advice.

[big61fourby]

Lets try this again...

I dosed pretty heavy with Power Service, and went for a drive. Made a few WOT runs, but it was too cold to get things very toasty. Will have a better idea tomorrow on my way to work, but the initial SOTP impression is that the turbo did actually seem more responsive, along with smoother running, less clatter, and less smoke. Can't help but wonder about ULSD. Really wish I could find a good tankful of LSD just for kicks and giggles...

The IP has at most 40 or 50k, but I really don't know about the injectors, so I suspect they are original. Worn injectors + marginal IP + ULSD = poor turbo performance???

Did you let nearly $200 go for an electric fuel pressure gauge? Ouch. At this point, I may just plumb an underhood mechanical gauge w/ idiot light. Any other options?

[DmaxMaverick]

You may have got a dose of gasoline in a fill up. Happens all the time, but usually to a pretty low degree. They put the wrong fuel in the tanks all the time. Depends on how much was in the storage tank, and how much they put in. Also, some engines are more sensitive to it than others.

Try running out the fuel you have, and fill up somewhere other than the last station.

[Hubert]

Yeah it was pricey somewhere around 200 with misc parts and it hurt but I am glad it is in and I know what fuel pressure is all the time now.

Good luck - Report back after a tank or 3.

[big61fourby]

Think I finally figured out what the deal was; Lucas. Price was really good, but my tank won't see it again.

Filled up today, and it ran noticeably better with just 27 gallons of straight #2, no additive.

Guess I'll still install the Hobbs switch and LED indicator. Can't have too many gauges/lights, right?

[TurboDiverArt]

Think I finally figured out what the deal was; Lucas. Price was really good, but my tank won't see it again.

Filled up today, and it ran noticeably better with just 27 gallons of straight #2, no additive.

Guess I'll still install the Hobbs switch and LED indicator. Can't have too many gauges/lights, right?
The place you filled up with #2, was it the same place you filled up last time you had the problem? Meaning, was the fuel the same or different? Depending on how much fuel the service station goes through and how often they get a new batch might give the same results. If it was marginal before, a fresh batch of good stuff might make the problem go away.

I have no opinion on Lucas stuff, as I have not used anything other than their transmission fix stuff in my transfer case. Probably should get it out at some point but some knucklehead before me put the drain plug in too tight and it won

[Hubert]

Clipped:


Think I finally figured out what the deal was; Lucas.

As in Lucas fuel additive?

Well keep us posted in 5 tanks or so. It can take a while for the fuel system to purge stuff like that.

I am not knocking any personal choices in additives and don't mean to start a loyalty brand name war. But yes name brands, and specifically the concentrations matter and have different effects.

Who knows the distributor or station might be adding a similar additive for bulk tank maintenance and when you dose your personal tank it compounds the concentration of certain additives. Then add in base fuel quality variables and fuel can be significantly different after a few fill ups.

[big61fourby]

I filled up yesterday at my usual spot, the 'biggest' truck stop in town. They have 3 islands with the high volume nozzles, separate from the gas pumps. That's where I buy pretty much all my fuel, and have only used a different station twice or so in the last couple months. I suspect they have a pretty high turnover, as they're really the only place within 30 miles that can accommodate big rigs on a pretty busy highway.

As for Lucas, I've used their oil stabilizer and trans fix in the past, with no noticeable improvement/detriment. As with their other products, the Upper Cylinder Lube is proportionally rather thick, and IMHO, too thick. I could see Stanadyne Blue or PS mixing much better upon fillup. I should also add that the Lucas I was using was older (possibly several years...:eek: ).

At this point, it's the only commonality with this issue.

[big61fourby]

Just thinking out loud here, would/could worn out injectors cause the 'lag' I was experiencing??

[DmaxMaverick]

Just thinking out loud here, would/could worn out injectors cause the 'lag' I was experiencing??

Short answer. Yes.