Has anyone ever tried to log fuel pressure? fueling issues

dbsharp · Post by **dbsharp** » Sat Jun 27, 2009 4:23 pm

I have been having a strange problem with my car for a while now. I would like to try to datalog my fuel pressure to be sure that is not the cause or part of the cause. I want to know know if anyone has done this before, and what equipment/ setup they used to do so. My problem: -occasional hard starts. -lean at idle occasionally (18-19+ afr). -random stalling (usually lean idle afrs during this event). -My tune seems to drift off over time. I tuned the my car to have around 14.5-15 afr through the part throttle. It stayed like that for a while and now part throttle is mostly 16-17 afr. It did this on crome too. -the other day during wot pull the car had a random lean spike. map, injector duration, and rpm were all consistent and steady throughout the run. Afr's were 13-13.1 and then there was a random lean spike to 14.1 for a brief moment. What I have done to correct this problem: -Replaced injectors -Replaced fpr -Replaced ecu -tried different tuning programs -tested injector wires and resistors, and other key components of wiring harness -ensured proper grounds -I have a walbro 255 with less than 20k miles. I also tested power supply and ground when I replaced it. -fuel filter is new What I plan on doing: -I have a new engine bay wiring harness that I'm going to throughly test before installing. I might also replace the ecu's wiring harness. -I want to test the pgmfi main relay -I want to retest/ possibly upgrade fuel pump circuitry -log fuel pressure -get some gas and torch the dam car, lol.

Post by **Bugermass** » Sat Jun 27, 2009 10:26 pm

The best fix for the problem.. Buy a new car..

Its so nice to have a new car that has no problems.. just drive it and put gas in it.. But, yeah to log fuel pressure isn't to hard, just get a el cheapo electric FP guage from the auto parts and run the outputs of it into a voltage input on the ECU.. Then you can datalog the pressure. I don't remeber which pinouts are voltage inputs off hand, I'm sure somone can chime in here and help with that.

pb16b · Post by **pb16b** » Sun Jun 28, 2009 12:47 am

throw any codes? i was having a similar problem and it turned out to be the pgmfi relay.

dbsharp · Post by **dbsharp** » Sun Jun 28, 2009 1:24 pm

no codes. LOL that would be too easy. \"The best fix for the problem.. Buy a new car.. Wink Its so nice to have a new car that has no problems.. just drive it and put gas in it.. \" God that would be nice. I want nothing more than a nice reliable dd. Gotta find a good job first. Thats hard these days even with a degree. Ill look into a cheepie electronic fuel pressure gauge.

thething96 · Post by **thething96** » Sun Jun 28, 2009 3:25 pm

I'm having the exact same issue, but my car runs richer than before, ever after retuning. I'm under the impression that it might be a map sensor issue.....

cbustuner · Post by **cbustuner** » Mon Jun 29, 2009 7:31 am

I'm going to try and log fuel pressure here soon.It seems pretty easy. Buy this sensor http://auberins.com/index.php?main_page ... cts_id=125 and a 1.29 voltage regulator at radio shack, wire everything up and just hook the output on the sensor to one of the 0-5v inputs on the ecu.That sensor even comes with the voltage tables to put in to ectune.

dbsharp · Post by **dbsharp** » Mon Jun 29, 2009 9:11 pm

Being the high roller that I am, I bought some glow shift gauges and an a pillar pod for them. I am upgrading my ricer status. lol. At least now Ill be able to keep an eye on fuel and oil pressure at all times. I am probably going to buy a main relay when I get around to buying my ac parts.

dbsharp · Post by **dbsharp** » Mon Jul 20, 2009 4:29 pm

OK fuel pressure is rock solid. I have a log where my afr is just going completely nuts. I don't think its the wideband acting up because of all the other fuel related problems I have, but I am not going to rule that out.