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Went out this morning to check the long term fuel trims after driving the car around, little to no change. On the passenger side it's down to 16% added fuel (idle), probably from just maneuvering a few lines around. I also created a small one on the driver side with a now 1% LTFC (idle). I totally see what you're saying now, under any load whatsoever the LTFC on the passenger side disappear and they immediately jump on the drivers side. My attempts to find vacuum leaks have been in vain, I'm going to call a shop on Monday and see if they've got a smoke machine. All other methods haven't turned up any results. I'm also going to redo fuel pressure test with my girlfriend watching instead of a friend, that or tape a phone to record it on the windshield to really exhaust fuel pressure as a possible issue near redline.
The vacuum leak is not the only possible cause. Could be an injector partly clogged, although that would appear as a problem under most load conditions. Maybe air leaking past a valve seal. I still need to contact Gary.
The vacuum leak is not the only possible cause. Could be an injector partly clogged, although that would appear as a problem under most load conditions. Maybe air leaking past a valve seal. I still need to contact Gary.
Yes that's very true, it's always kind of a guessing game in this situation. I finished testing the fuel pressure once again, this time with my own tester. Mine isn't long enough to reach the windshield so I taped my phone and a flashlight in place under the hood and took a video with my phone. Surprisingly it worked well, got up to 5,700 rpm in 1st gear (Would have done more but lots of cops out), dropped by a single psi from 42 to 41psi at around 5,700.
Over the weekend I built a smoke machine that I saw on youtube, best $11 ever spent. Works phenomenally well. Used it to try and find vaccum leaks and I couldn't find any but a slight weird one. No leaks from any vacuum lines, injector o-rings, intake manifold gasket, brake booster etc.. I've attached a photo of where smoke is coming from what seems to be behind the throttle springs, not the throttle body gasket, actually behind the springs themselves. That and a small amount from the cracked IAT rubber seal that I previously posted a picture of. I built up quite a bit of pressure to see it come from the springs. I'm going to drive the car a bit and see if the PCM has re-learmed any of LTFC's, may datalog at the same time.
The TB leak would be the shaft seal, and I have no idea if it is a real seal or just a tight fit of the shaft to the bushing. On the other end, with the TPS sensor, there is a replaceable foam seal around the shaft. But maybe the shaft is seriously worn and the gap has increased. The leak at the IAT sensor is not really a vacuum leak. But it is air bypassing the MAF sensor and could cause a need to increase fuel flow using the LTFT's. But again, there is not a lot of negative pressure (vacuum) in front of the throttle blades.
I can't see either of those being a large enough leak causing a 19% fuel short fall, and only on one bank.
The TB leak would be the shaft seal, and I have no idea if it is a real seal or just a tight fit of the shaft to the bushing. On the other end, with the TPS sensor, there is a replaceable foam seal around the shaft. But maybe the shaft is seriously worn and the gap has increased. The leak at the IAT sensor is not really a vacuum leak. But it is air bypassing the MAF sensor and could cause a need to increase fuel flow using the LTFT's. But again, there is not a lot of negative pressure (vacuum) in front of the throttle blades.
I can't see either of those being a large enough leak causing a 19% fuel short fall, and only on one bank.
Yea I totally agree with you, neither of those could account for such a short fall in fuel and even if it was effecting either bank it would be both. I can tell you without a doubt at this point that there are no vacuum leaks whatsoever that could possibly cause this, and fuel pressure is stable at 41-42psi under the conditions in which the issue is occuring. What other options could be left? An injector on the passenger side acting inconsistently? I checked for exhaust leaks quite liberally and couldn't find a single one, not before or after the oxygen sensors. I took another datalog right after doing the vacuum leak test, I can upload if you would like to compare it to the first. Just glancing through the LTFC's on the passenger side (bank 2) were sitting around 2 at idle during the first 5-6min of the datalog. The longer the car drove, the LTFC's started moving back towards 19 on bank 2 (at idle). Could this be pointing to an issue that occurs once the car has warmed up partially?
I re-did my exhaust leak test, this time with a vacuum cleaner blowing and some soapy water to find the leaks. I found a few and fixed them up. I'll drive the car to see if the LTFC's change at all. Is it safe to bet on either a spark plug or fuel injector issue? I've got new NGK TR-55 IX plugs that you recommended, gapped @0.045. The one's still in the car are the double platinum ones that I posted pictures of in my Standard Style Distributor post. Someone mentioned that the gap was a little large, atleast in the picture. I've also got the rebuilt Bosch 3 injectors from Fuel Injector Connection ready to go in. You're much more knowledgeable on a subject like this than I would be. Does it make sense to put in the new plugs, new injectors then order Solomon's cable loan method for tuning and go from there? Even if putting the new components in doesn't solve the issue, his tuning software may have more data which could be useful to solving the problem?
Current update, after not finding any weaknesses in the fuel system, not finding any exhaust leaks or vacuum leaks, and all other tests performed up above, I decided it was possible the car had constantly varying fuel trims due to a slight misfire from the Carquest opti spark in the car. I decided to invest in a Petris Optispark since I figured it was only a matter of time before the Carquest took a dump or caused other possible issues that would cause me to chase my tail. I wasn't wrong, I removed the Carquest opti and immediately noticed several things wrong once I popped it open (other than the immediate sound of something loose inside). The two screws in the picture below had completely backed out and were just laying as pictured. Another thing was that it appeared as though the slotted metal disk (unsure of correct name) actually had enough play to contact the optical sensor and had scraps and marring across the surface. This may have been due to the two small screws backing out first. My Petris opti is installed now and the car has a noticeably smoother idle. I haven't had time to really beat on it, but I would bet it feels a bit stronger as well. In the process of taking everything apart, I re-installed my factory coil (Had an MSD Before) and cleaned all the old thermal paste off the ICM and re-applied some. Moral of the story, don't cheap out on an optispark, this is the second Carquest one that had failed within less than 300mi. I'm not even going to try and warranty it, I wouldn't go to the labor of installing and removing it just to have to pull it out after 300 odd miles. It is now a paper weight on my desk. I'll have to drive the car for a bit, then I'll check the LTFC's. The previous tune is also looking slightly suspect at this point, I have no definite knowledge of who tuned the car however.
08-08-2020, 10:23 AM
