Thales

How is it that your MAF reading is higher on the hot run?

Hot run: AIT way up, MAP down = way less particles going in, no?

User 52121

I agree - that would certainly make sense. I didn't have a lot of time last night to mess with it (gotta be careful how much time I spend with the Mistress or the wife gets jealous) but did inspect all the vac and boost hoses again, didn't find anything wrong. Pulled the plugs, they're due to be replaced.


Josh's tuner/logger is seriously awesome and makes troubleshooting a LOT easier. I keep forgetting I have it. I love that I can make a few runs, log it, then review it frame-by-frame later when in the house, or on the train commuting, or on my lunch break....


Running a factory DME with Rogue Tuning's tuner/logger setup. http://www.roguetuning.com/rogue_tuning_dme_tuner%C2%A9

And yes there is an AIT Compensation table that alters the main fueling table based on engine load and AIT. I don't believe that the table is "wrong"... it's an off-the-shelf map from Rogue and others don't have this problem. But the car IS running rich (even on a good day) and I wonder if the hot weather just exacerbates it.

Did some brief screwing around this morning before leaving for work. It was cool outside (upper 50ss) and I wanted to grab a quick log. But I forgot I yanked the plugs out last night, and I couldn't see putting the old crusty ones back in so I broke the cardinal rule (only change one variable at a time) and swapped in a fresh set and went for a quick ride.

IAT's between 60-65F. Car ran great, as strong as it's ever been when running good (in other words, "normal" IMO). AFR's 10.7-10.9. MAF volts 3.33.

Have to borrow a fuel pressure gauge from my dad, will test the fuel pressure tonight to see that it's all in order.

I'll post the logs with some charts later after I get a chance to mess with them at lunch.

blown 944

Considering the conditions, it looks like you may be a little rich to start with. I'd certainly look at doing an intake pressure test. The couplers at the IC can be cracked and the turbo would be working harder to reach target boost pressure and therefore reading more MAF voltage as noted earlier.

User 52121

This morning's log attached.

User 52121

Yeah I discovered a cracked IC coupler last fall while at Road America and replaced both of 'em with new OE parts.

I will pressure test this weekend when I have a couple hours to kill just to rule out the possibility but I find it odd that the car only leaks boost when it's hot outside (?)

blown 944

It would be leaking all the time. The air is more dense in cooler weather, so the AFRs would be closer to correct. When it's warm, with the air being thinner, the problem would be exacerbated. This goes along with the evidence of the higher MAF readings ie; when cooler it would hit target boost easier. When warm, you are compressing hotter air and the percentage would change, both in airflow in and what is lost to hit target boost.

User 52121

Alright alright alright, jeeez!



Will pressure test this weekend. It's certainly the only logical conclusion to what the problem is.

Didn't get around to testing fuel pressure... borrowed gauge wrong one. A trip to Harbor Freight is in order.

User 52121

PS - thx for all the help guys. RL rules. As usual.

User 52121

Ok had a quick second while the wife is out. Fuel pressure too high. Looks to be 47psi or thereabouts with the vac line off. Genuine Bosch 3 bar FPR.

Next will be pressure test the intake.

User 52121

Ok found a few leaks. They seem small (?) but I have nothing to compare it to, to know what's normal.

For sure my BOV was leaking. Fancy billet unit that can be disassembled and cleaned/rebuilt... the big nipple that connected to the upper IC pipe at the TB was loose. So I pulled it apart, cleaned, taped and tightened.

Also have some leaks from the TB shaft. Ordered a TB seal kit already, so will put that together.

I can feel a tiny stream of air where the 2-port banjo threads into the intake manifold. I'll do something with that.

Otherwise I *think* I hear something from under the manifold but not sure, it's hard to tell where it is coming from. If I stand in front of the car, it sounds like it's coming from under the manifold. But if I stand on the side of the car, it sounds like it's coming from the TB.

All in all it's hard to say if it's "bad" or not.... but we will see once I put it all back together I guess and pull fuel out due to the high fuel pressure.

blown 944

It is probably due to the high fp vs the leaks. However, the leaks certainly make it worse. I use a "smoke" leak detector and it is awesome. It uses heated baby oil that makes a smoke vapor and I'd pressurized in. Not sure if you can figure out a way to do this but it makes finding leaks easy

gregeast

Best luck I've had finding leaks is to pressurize the system and then spray some diluted dishwasher soap out of a spray bottle anywhere you think you hear leaks, the resulting bubbles make it pretty easy to identify the problem area.

And I'm glad to know Syd has a smoke tester, I live in a good 944 'neighborhood'

User 52121

Yeah starting to wish I lived in Colorado! But then my wife would probably see even less of me, I'd be hanging out at Joshua's house or Sid's garage trying to get a peek at what's next!

Using a pressure tester built by "thales" above.. pretty slick, I'm going to copy it. Or maybe just never return it. Way better than my PVC pipe concoction I came up with (and eventually lost) the last time I went hunting for boost leaks. I'm sure there's a way I can modify it to inject smoke... but for now, I think I'll reseal the TB, fix the BOV, fix the leak at the banjo on the manifold, and lean it out some, and see where that gets me. If I still have issues after that I will move on to smoke injection.

gregeast

Arnnworx has a pressure tester for $16.98 if you don't feel like building your own.

http://www.arnnworx.com/catalog/inde...roducts_id=239

User 52121

Ok rebuilt the TB. The TB shaft seals weren't really seals. More like clumps of dust arranged in a circular pattern around the shaft. Going to reinstall today hopefully and see what I get...