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squirreljuice
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Discussion Starter · #1 ·
Alright, I have decided to clean up the previous thread that was all over the place with things and just start anew. For those that wish to read my antics from the past couple of years, follow this link:

http://newbeetle.org/forums/1-8-liter-turbo/101409-running-rich-lean-same-time.html

To sum up, in the beginning I was experiencing some codes from my car that state the car is running lean, and then it took off from there. I am still experiencing a lean condition, like the car runs out of fuel at the top end and will cough and sputter from 3k rpms on. The charging issue has been fixed; the offending cable and fuse box have been replaced. Over the course of trouble shooting this, I have:

-Replaced clutch in January of 2015 due to separating the inside, splined plate from the actual clutch material
-Inspected the exhaust for leaks, found one at the turbo manifold, fixed it, no current leaks.
-Inspected the intake system, no visible breaks or leaks in there
-Logged ECU data, drop box folder is at https://www.dropbox.com/sh/wwxj4mlaa...G6Cr-4HQa?dl=0
-Replaced fuel pump, FPR, and fuel filter, all with brand new, OEM Bosch units
-Car is running on DV (was BOV previously), and stock 3 bar FPR
-Throttle body has been cleaned and aligned
-DV is clean and functioning properly
-Electrical gremlins have all been ferreted out (to my knowledge) and everything seems to be working as it should electrically.
-MAF is a newer unit, but I don't think its an actual Bosch
-N75 replaced 4 years ago when trying to fix boost flutter
-Serpentine belt replaced twice in the last month, the first just because I had the alternator off and figured may as well while I'm in here and the second because that belt was flawed and broke. I'm sure this has nothing to do with my current problems but you never know what small changes have on other things with these cars, so I figured I would list it with everything else.

Suggested to be replaced so far are the upstream O2 sensor and the MAF, which I have not ordered yet as I don't want to just keep throwing money at this car. The coolant temp sensor has also been suggested, and I will probably try that first, based on my findings outlined below.

Back to the lean condition...

The car feels like and acts like and shows in the AFRs that it is running out of fuel at rpms approaching 3k and above. I went back and re-pulled the fuel pressure levels and I am getting 2.5 bar with the pump prime before engine start and 2.5 bar at idle with 10 hg (-5ish psi) of vacuum. Reving to the cough point of 3k rpms brought the fuel pressure up to 3.75 bar at 10 PSI of boost. Both boost and fuel pressure would climb no higher than that due to (I'm guessing?) the coughing and sputtering at the 3k rpm mark. To me, these seem to be on the low side, but I will let someone else chime in on that.

Reviewing the new logs from last week when I last drove the car to work on it, the car does sit at an average warmed-up temp of 190 degrees F, which is lower than I think it should be. Most other cars I have seen sit between 200 and 220. The ambient air was around 75 to 80 degrees on the day of the drive, unlike the first few logs where it was between 20 and 30 degrees outside. So I may have a temp sensor to replace.

Mass air flow readings seem to move between 2.5 and 3.5 grams per second at idle when warmed up, which seems to be in the ball park of what sr. member jfoj pulled from his 1.8T bug at idle, so it *seems* like my mass airflow sensor is currently working. Again, I'll let someone else with more experience chime in here and correct me.

Spark plugs have all been pulled and checked for signs of damage and all of them look like they should for 30k miles on them. They were all still gapped correctly, were not oil fouled or charred or visibly damaged in any way. Coil packs are all in good condition and seated properly in the head.

All visible and readily accessible vacuum lines have been checked for integrity, and some bad ones have been replaced. All have been checked for proper seating on their ports.

I also decided to run some Lucas Deep Clean fuel system cleaner through my car. I figured it wouldn't hurt, and there is probably a good amount of gunk built up in my fuel system (to my knowledge no cleaners have ever been run through the car). So far it seems like it has helped even out the cough and sputter and I've even gotten a few full-power pulls out of the car while this stuff has been working its way through my fuel system, so there might be something that's getting worked out by the cleaner. But, it could also be the cleaner causing that, so I'm not sure at the moment about that. I'll update on that when I finish out the tank of gas its on and fill it up again.

With the data I have it seems to me like my first course of action should be the coolant temp sensor and possibly yet another FPR and/or O2 sensor after that, but the current tank of gas should be finished out before I start buying more expensive VW parts.

What do you guys think? And let me know if I missed anything from my previous thread and I will address that. I'm sorry that this has been ongoing for a while and I haven't always had data to give you, but I think I have all the basic diagnostic equipment that I need (finally) to keep you guys informed of findings and give you more accurate things than just a "butt-dyno" of the car.
 

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DropBox link not working or does not link to a file.

I just drove my 2003 1.8t convertible 1200 miles and I had my UltraGauge installed. Top down for 1100 of these miles! :D

Watched the temp for the entire drive and it generally settled right at 205F while cruising. Occasionally while coasting down hill or on very light throttle the temp would drop to 199F or so, but would quickly settle back in around 205F. This was at speeds up to 80 MPH for extended periods of time, I started out with ambient temps in the low to mid 50F's and by the end of my trip was even in town at 96F ambient. In traffic and stopped idling the temp would usually settle around 210F.

This was with a new, aftermarket, thermostat, and after replacing most hoses and plastic coolant interfaces on the engine.

Be careful on the coolant temperature sensor replacement, ALL VW forums blame everything on the coolant temperature sensor, but I can tell you 100% for sure the thermostats are FAR more trouble prone than the coolant temperature sensors. The thermostat I just replaced was a VW dealer sourced thermostat that was about 3 years old and it was going soft again. I just happened to have an aftermarket thermostat that was provided with a BlauParts cooling system kit that I did not install previously laying around, so I installed it and it works perfectly. What I liked/noticed is it actually had a threaded adjustment that allowed the thermostat to be fine tuned at the manufacturing plant and it appears this has been the best thermostat I have found for the car to date.

You really need to get warm idle and steady highway cruise Fuel Trim baseline values to see what is going on. My car would have LTFT on this 1200 mile trip from 0% to +2.5% depending on the conditions the car was driven under. Those fuel trims are exactly what I expect to see in a well running vehicle. I was actually a bit surprised at times to see the fuel trims drop below + 1.5% and even to 0% but never to a negative value.
 

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squirreljuice
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391 Posts
Discussion Starter · #3 ·
Sorry to resurrect this old tired thread, but I just wanted to thank everyone who was trying to help me get this figured out. I also wanted to post some closure, as we finally figured it out.

The turbo died.

Found that out after I gave the car to a machinist who wanted the transmission for a lathe. He tore it apart and found that the turbo had over 1/4 inch of shaft play and the compressor housing was badly scored and grooved. The flutter was due to the turbo locking itself up against the compressor housing, causing less air into the engine than anticipated, and causing the misfires.

Mr. Bug lived a long happy life and I miss him dearly. He will always be my favorite car, and will always hold a very near and dear place in my heart.
 

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Thanks for reporting back; on the final conclusion, to your problem. A bad turbo; can certainly cause, many issues that are unable to be resolved by outside peripheral factors you try to work with. I had a 1.8T A4 i was working on and really struggled with a bunch of drivability issues it had and finally discovered the turbocharger housing had a hairline crack in it (a new turbo fixed it). Thanks again; for providing the cause to a unresolved thread! :)
 
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