Still working on this issue. I've now:

- Replaced the exhaust flex joint - entire exhaust is in good order now
- Did the wastegate swap
- Replaced the two engine fuel filters (haven't done the tank filter)
- 2 or 3 diesel purges
- Timed the Injection Pump

And the '92 300D still drives with ZERO power. I have another '92 300D and a '93 300D and they take off so there is clearly something wrong.

No vacuum leaks - been through all the hoses. Transmission shifts fine - no issues.

I'm going to try pulling the ALDA now that I have the wastegate swap in place.

At this point - I'm thinking it is either the Injection Pump or the turbo itself.

Thoughts?

-John

From what I have read you have not put a pressure gauge on your alda. It does not operate with a vacuum but with intake manifold pressure.

I would also suggest that plumb a boost gauge into your intake manifold so that you know how much you are getting.

I took the working ALDA off of my car. I have noticed a bit of pickup increase at low speed but it generally does nothing substantial except to limit the fuel at low speed. Nothing that you can not do with your right foot. If your Alda does not work it will keep the fueling and subsequent power low. The turbo needs to have fuel to get exhaust flow.

Ok - spent a few hours on this issue today. I've replaced every hose on the engine at this point and cleaned out the ALDA connection from the intake manifold.

I've connected a T to the line going to the ALDA and under heavy load (peddle to the floor while driving) I peg my pressure gauge at 10 PSI. It hit the max peg hard enough that I'm pretty sure it's getting 12-14 PSI.

I've timed the Injection pump - no change.

I've replaced the fuel return lines from the IP - no change.

I've replaced both the fuel filters - no change.

I've replaced the fuel return banjo bolt on the engine side of the IP - no change.

I've swapped out the wastegate following the pressure wastegate swap that many here have done - no change.

I've checked for full motion of the throttle linkage when someone pushes the peddle to the floor - looks good.

I've connected a small fuel container and used that for testing to see if the fuel supply was the issue - no change.

I have a identical '92 300D and it is FAST compared to this one.

Other than replacing the IP or the turbo - what else can I try? Engine starts with NO issues and there is no smoke of any kind - even under load.

I'm pretty certain it's a fuel source issue - yes?

Thanks,

-John

Add to the above list:

- Swapped the lifter pump (shot in the dark) - no change

-John

have you stopwatch timed a 0-60 run on flat ground?

I just completed a test - the road was slightly down hill.

0 to 60 was 25 secs. My understanding is this car should do 0-60 in 12-14 sec's.

-John

Did another test on a flat road and I'm getting about 30 sec's from 0-60.

I'm getting ready to pull the IP unless someone stops me from thinking crazy!! ;)

Please... stop me. I'm not crazy about the idea.

-John

I thought for sure I would get a bunch of flame messages when I suggested pulling the IP.

I'm planning on disabling the turbo on my working '92 300D to see what the performance test is like. If the #'s are still way off I'm going to pull the ALDA. If no improvement there I'm going to pull the Turbo before I do the IP.

Sound like a reasonable plan?

-John

Did you pull the ALDA? This is a first page step in the diagnosis sequence, not fourth page :)

Since you have access to other 602s, does the turbo shaft of the slow one feel like it has more drag than the others when spun by hand with the engine off?

Are you ready to spend ~$800 on an IP rebuild? If not, don't bother pulling the IP.

Sixto
87 300D

How much boost are you getting now? As previously mentioned tee into the intake line going to the alda and get a boost reading. If it is making boost then the problem is more likely fuel delivery.

My guess would be that the alda isn't plumbed/opperating correctly.

Have you bypassed the overboost protecion "thing" and run the alda straight off the intake?

Getting the pressure readings from your lift pump to the IP and then again from the IP to the injector will let you know what is going on there if that is the problem. Might be easier to test before just taking off parts and putting new ones on....IMO

Thanks everyone for the points.

Yes - the ALDA was removed way back toward the start of this - with no change. But so many other things have now changed I thought it would be a good idea to pull the ALDA again.

Also toward the start of this working this issue - I reached in and spun the turbo shaft to check for binding and/or play in the shaft. No clear signs of any issue.

I have a spare IP from a parts car that I know works - so was thinking of swapping IP's - and not a rebuild.

OK - HELP me understand the overboot protection "thing" - where/what is this? I've seen posts mention it - but I don't know what it is and what it does.

Thanks,

-John

IIRC overboost protection is a 90-91 thing not installed for 92-93. Otherwise there's a switchover valve in the line from the manifold to the ALDA which is energized when a manifold pressure sensor sees 1.1 or 1.2 bar. I don't know where it is in a 602 car but in a 603 car it's on the port shock tower just ahead of the windshield washer bottle. Follow the line from the ALDA back to the manifold.

One possibility possibly suggested already (I didn't go back through the thread) is a stuck IP timer. It has a centrifugal advance which can get stuck. I've never heard of such a failure, though. The FSM discusses the advance curve for the IP timer but you need some fancy RIV equipment even gsxr doesn't have to measure IP timer advance. Maybe one of those clamp on injector line pulse sensors will help but they're $3-400 plus a timing light.

Sixto
87 300D

Ok - so 90-91 300D's - that would explain why my two 92's and my '93 don't have anything between the intake manifold and the ALDA (just a straight hose).

I'm going to try pulling the ALDA and do another test.

Thanks everyone.

Bump
 

Curiosity and end result.

Ok - did some work this morning on this issue. I pulled the ALDA (again) - but I figured it was a good thing to do since so many other things have changed since I pulled it originally (new pressure waste-gate mod, etc - see list in previous msg).

I also did some tests with my "cream-puff" '92 300D. I marked/timed a 0-40 mph test area and found:

- Everything as it should be: 0-40 mph in 9+ secs
- Disconnected the ALDA and plugged it: 0-40 mph in 18 secs
- With the ALDA disconnected I disabled the turbo (computer controlled) wastegate: 0-40 mph in 18 secs (as expected with ALDA not functioning)

I then did some tests with the "issue" '92 300D. Same 0-40 mph test area and found:

- Everything as it should be: 0-40 mph in 18 secs
- Pulled the ALDA from the IP and plugged it: 0-40 mph in 13+ secs

And I *think* I heard the turbo whine a little with the "issue" '92 300D - but I'm not sure but it does seem to be pulling a little harder.

I'm pretty sure it's fuel related. Even with the ALDA pulled from the IP - I'm not getting any black smoke out the back.

I'm planning on driving the car for a while with the ALDA off and see if the performance changes in anyway over time. I believe this is a safe thing considering the way the car is behaving.

Any other things I could try? Still thinking of swapping the IP with a spare.

-John