Quote:
Originally Posted by rwest
I can’t give you a definite answer, but can give a few thoughts. Around town, you are stopping and going, on the freeway, once you get to steady speed, you keep it there.
So, is there something that is causing a bunch of fuel to “dump” into the system when first applying the pedal? Maybe a distributor issue not properly advancing or retarding until it spins up fast enough?
Good luck, it will be interesting to see what the cause is.
|
Rutager... Thought the same about steady throttle and variable and the answer being in there. Installed wideband and the city traces don't show any sign of full dumping. Distrib is in good order. Well lubricated. Just looked inside to confirm.
Quote:
Originally Posted by ErrorMargin
Just a thought: are you sure the correct cams are installed and timed correctly?
|
EM... 964 cams from Webcam were installed with rebuild. 40/40 grind. 2.45 Overlap matched perfectly both sides. I may have said 1.45 earlier---will look and correct if I did. According to Webcam, Cathy as I recall, these cams are suited to a 3.2. She advised a more aggressive overlap than stock 2.25. I've discussed mods done to engine with one who knows much more about air-fuel than I. Cams, SSIs, Dansk muf are not the cause---there's something else.
Quote:
Originally Posted by GH85Carrera
One track day at Charlotte Superspeedway, I was told to fill up before the day of track fun. I filled up agin before going back to my hotel, and did the calculation of about 8 MPG. There is a LOT of WOT on track. I can't imagine you can do anything like that on the street.
I know you have been chasing that issue for a while. The fuel injectors should not dump enough fuel to get that poor of mileage without a lot of air to go with it.
Have you had the oil tested for fuel contamination? Even if there is gas in the oil, one tank of gas would have the oil system purging oil from overflow. Maybe some is getting into the oil however.
Have you tried a exhaust gas sniffer at the tail pipe to read the A/F ratio?
We all want to know what your solution is.
|
Glen... Have not had oil tested. Did change crank oil not long ago and it looked as I think it should. No sniffer. With wideband system tested and parts and software replaced to pizz away money, the data did not change no matter what was done so have to believe wideband data is accurate.
Quote:
Originally Posted by Techno Duck
What DME chip are you using, stock?
I'm assuming you are not running the narrowband o2 sensor since you state only 2 bungs and both have wideband sensors for logging.
AFR during city driving looks very lean. Cruise AFR looks normalish, maybe a little lean. WOT looks to be expected.
What is the history on the air flow meter (AFM)? Is it the same one that was on the car prior to rebuild? Any indication it was ever opened up previously? When i bought my car, i found the clock spring in the AFM was adjusted to make the car run lean, no doubt to get it to pass emissions. Its possible your rebuild fixed a few issues a misadjusted AFM was hiding, so now the car is running leaner as a result. At WOT the car defaults to a preset fuel map which looks to be reflected in your datalog.
Interesting you are getting such mad mileage. Is their any other indication of this? Rich smelling exhaust? Sooty tail pipe / bumper? Smoke from tailpipe during idle / accelerating?
How was fuel pressure checked? Does fuel pressure match the normal spec at idle? (i forgot what it is). How about when you pull the vacuum line off?
|
Jon... chip is stock and has been confirmed correct for '85 3.2. ECU was also tested and "No Faults" found. (I still question this testing.) AFM has been opened by me... to check sweep track. Is marked but test of sweep proved it working across its full range. I also messed with the spring tension but put that back to where it was. Fuel setting was also altered from 0 to 3 and returned to 0.
Your idea of the rebuild fixing things and now the AFM being out of sync---I trust you mean runner richer rather than "leaner." If this were the case, would the wideband logs not reveal this?
Soot in the tail pipe was the first indication for this journey. Then the fuel gauge didn't look right. Fill at the pump confirmed. This journey then began. Now, no soot. Never been any smoke no matter the throttle. Gas smell there used to be with nose stuck in pipe. With the testing, adjustments here and there, it's impossible to know why the soot is gone. I keep records but keeping track of each small detail doesn't happen. I genuinely thought wideband was the holy grail here. So far it has added to the mystery as there's no sign of when the fuel is dumping.
Fuel pressure was checked at the 1-2-3 rail port. Was good as I recall. Flow was also checked but out of the rail rather than after the pressure relief valve as was suggested it should be.
Vacuum... remove oil cap and engine suffers. Disconnect brake booster line and engine suffers.
I appreciate all the ideas / input. Whatever is going on, the answer(s) will be found. There's no giving up here.
.