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High EGT's, low boost, WTF? by lord_verminaard on 21 May, 2010 07:29
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Ok, finally have had a lot of seat time in this Golf after countless problems.
First of all, it's back to running an N/A pump for the time being until 10 years from now when I can afford a Giles pump.
Some more background info:
NA block, solid lifter head
Engine rebuilt, used thickest MLS head gasket to lower CR a little. Pistons are Swaintech coated.
Head had a valve job, and is mildly ported, intake ports are D-shaped now.
Back to running a stock VW TD T3 and exhaust manifold
TDI intake manifold, mildly ported lowers.
No intercooler right now.
I don't know where it is timed, I guessed.
Overall the car runs pretty well. Starts INSTANTLY, hot or cold, now that I have new glow plugs. I usually use the cold start lever for about 5 minutes, seems to be smoother that way. Good power when driving normally, though I basically don't get any boost at all until I rev the piss out of it. That is, normal traffic acceleration to 35 MPH shifting normally, there is no boost. I can hear the turbo starting to spool but nothing on the gauge.
I have the pump turned up a bit, there is some smoke off-idle until a little higher in the RPM's, but not much. Using light pedal, there is no visible smoke from the rear-view.
Driving at 55-65 mph, (guessing since the speedo does not work) EGT's go up pretty high, will hover around 750 but even a slight increase in throttle pedal for a hill or something and they shoot up to 1100-1200 pretty easily. No smoke and no boost during this time. Unless I am going very fast, like probably 75 mph or so, there is no boost in 5th gear even with the pedal floored. Driving on the highway at those speeds, EGT's are usually 950 at the least, sometimes going to 1350 or so if I have to speed up a little but usually they hang around 1100.
If I try to accelerate hard from a stop, I'll get maybe 10 psi in 2nd-3rd-4th. EGT's usually don't go very high when doing this, maybe 1100, and there is no smoke except for a little between shifts when I get back on the throttle. But spool is VERY late. If I had to guess, I would say 3000 RPM's or so before you see anything.
Now, when I had the TD pump on it, it would hit about 18 psi or so and I could hear the wastegate opening, so I know it's not stuck open. EGT's were still pretty high, and the boost still was very late coming on, but it did come on a little sooner and climbed faster. There was some smoke though.
I know the NA pump is holding it back some, but if there is enough fuel to smoke a bit off-boost, there should be enough fuel to spool the damn turbo. Plus, EGT's seem way too high to me when I'm barely using any throttle to keep up at 55-65 mph.
The car does feel pretty slow, fast enough to merge on to the highway without worrying about getting run over, drives through town really nice but not very quick. Off-boost power in the lower RPM's seems pretty good. Better than my Audi even.
Anybody have any ideas what's going on? Could it be a timing issue? How does timing affect boost and EGT?
Thanks in advance-
Brendan -
#1 by burn_your_money on 21 May, 2010 09:50
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What size exhaust are you running? You should be making boost on the highway, 2-4 psi while cruising.
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#2 by lord_verminaard on 22 May, 2010 06:25
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It's 2.5" turbo-back.
There might be a chance there is a small exhaust leak at the manifold-to-head or possibly turbo-to-manifold. I noticed a puff of smoke from that area when I was revving the engine by hand the other day after making a tuning adjustment. Could that be causing all of this?
Brendan -
#3 by burn_your_money on 22 May, 2010 06:54
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I think that could do it. My brother's AAZ had a nasty exhaust manifold leak and he always had high EGTs. He didn't have a boost gauge so I can't comment on that. Unfortunately the leak wasn't discovered until I was tearing the motor down
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#4 by lord_verminaard on 22 May, 2010 12:08
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Welp, I guess I'll start there. Going to do an oil change here in a minute so I'll try and re-tighten everything while I'm under there.
Brendan -
#5 by 8v-of-fury on 22 May, 2010 19:27
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How did this turn out Brendan?
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#6 by lord_verminaard on 23 May, 2010 04:22
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Well, the bottom 4 exhaust manifold nuts were loose, I got about a 1/2 turn on them to tighten them back up. I also managed to turn the top leftmost and rightmost nuts a little, but the 2 in the middle I cant get to with the turbo on there. The turbo bolts were super tight and didn't budge. Didn't fix it, unfortunately. When I started it up and revved it a bit, I could still see a little smoke under the hood from somewhere back there. So it's either the two in the middle, or something else. Anyone had any success getting to those two nuts with the turbo still on?
Brendan -
#7 by lord_verminaard on 26 May, 2010 11:40
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Update- this actually did seem to help a little bit. Boost comes up a tad bit quicker under normal street driving, though still a lot later than I think it should.
On the highway, I'm still not making any boost, but it does start to build almost immediately when I apply more throttle. EGT's during highway driving are down about 100* F or so but still climb very rapidly.
I guess I need to figure out how to torque down the other two nuts before I go any further.
Of course, right now I blew out the dipstick tube seal because of an improperly installed catch can, so I have that to deal with first.
Brendan -
#8 by Wayland on 18 Aug, 2010 22:33
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Did you ever figure out what the problem was? I just got my NA-TD conversion on the road today and seem to be having the exact same problem.
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#9 by honda_is_the_best on 19 Aug, 2010 09:44
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I think that could do it. My brother's AAZ had a nasty exhaust manifold leak and he always had high EGTs. He didn't have a boost gauge so I can't comment on that. Unfortunately the leak wasn't discovered until I was tearing the motor down
leaks just makes the turbo a big restriction if its leaking drive pressure. its gotta be sealed to the exhaust manifold and head perfectly. any leaks are bad news.. -
#10 by Smokey Eddy on 19 Aug, 2010 10:51
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I've had countless boost leaks.
Check all your piping. adding an intercooler will drastically reduce the EGTs and MASSIVELY increase the torque.
I've had my T3 leak where the cold side housing mates to the turbo. there is supposed to be a gasket there but mine didn't have one so i RTV'd it and put it back together. fixed the leak. but it would leak almost all the boost through there.
look for a huge oily mess. thats where the leak will be.
if your exhaust is leaking to the point where it isn't driving the turbo the exhaust smell in the car will be very strong but more noticably the car will be incredibly loud especially under load. -
#11 by rodpaslow on 19 Aug, 2010 11:39
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Just as a note I have a 92 TD with 2.5 exhaust with a tach. (1.6) Mine starts spooling at 2500 rpm under load an hits about 20psi by about 3200 rpm. I have mine limited to that. with my 020 tranny and a .71 fifth I drive at about 2900 rpm at 120 kph. I don't see any boost unless I go faster. But at 2900 rpm if I hit the throttle boost is instantaneous. No boost showing at a cruise state. This is also a T3.
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#12 by lord_verminaard on 01 Sep, 2010 08:08
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Almost forgot that I posted this.
No real updates to report. I've been up to my eyeballs in projects so I have not had time to mess with it. I finally got my Audi back on the road and my Wife isn't working right now so the car is not getting driven too much.
It actually drives very nicely but just low on power. Once I finish and sell the Corrado, I plan on pulling the turbo, re-sealing the cold-side, fixing the stupid oil drain line for a 10th time, torquing all of the manifold nuts to god-tight, and re-assembling everything and adding a front-mount that has been sitting in my garage for months. That's all she's getting this year while I finish up all of my other crap that I have to do.
I also have to come up with the money for an injection pump rebuild- maybe winter time so it is ready to install in the spring. (spare TD pump to replace the NA one)
Brendan