Newbie ForumBeginner/newbie/general DSM questions. first mods, how to run 10's when you haven't run 12's yet, any tech question that doesn't fit in another tech forum. New Members must limit their tech posts to this forum and sub-forums.
Hi, I've read different posts similar to my situation, but can find any solution.
I recently rebuilt the head (replaced everything except rocker arms). I put everything back together and did boost leak test (fixed leaks). Everything is stock, except for a Walbro 255 fuel pump. I do a have a fuel regulator and lowered it to 42 psi (vacuum disconnected).
When I start up, my logger shows the O2 sensor reading at around 0.20, but rapidly (after 1 - 2 minutes) goes to about 0.95 - 1.01 and fluctuates between those. The Wideband shows 10.0. I don't know what else to do.
BTW, I discovered today that one of the wires for the knock sensor was broken from the connector. Would this also cause it to run rich? Thanks in advance for your help.
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The fuel pump was put in before I did the rebuild and the car was idling fine - around 14.5 after it warmed up.
I don't have any CEL's. I found that strange too, since the knock sensor is broken.
It reads 10:1 during idle and even when driving. It's so rich, I can't do WOT. While drive with about 10 psi, it'll go between 12 - 13:1, but cruising or coming to a stop, it's at 10:1. My spark plugs are black and I have to keep cleaning them. Any suggestions to this madness?
What kind of fuel pressure regulator do you have, for some reason it sounds like its being over run and thats causing you to run rich at cruise and idle. Rememer at wot I believe our cars have a stock afr of about 9.4:1-9.6:1. The wbo2 only reads as low as 10.1 so that is normal.
What do your FT's look like when the O2 voltage shoots up? Also, what airflow number is your logger showing at idle? Does it change when the O2's go through the roof?
The FPR isn't stock but an aftermarket. I don't remember where the shop got it from or what brand, but it had cost about $30 on the bill (2 years ago). On WOT it sputters and lags a lot. I do have a log in csv format. Is there a way to upload it to the post? I'd really like someone to take a look. Thanks!
What do your FT's look like when the O2 voltage shoots up? Also, what airflow number is your logger showing at idle? Does it change when the O2's go through the roof?
Sorry, still new here. What is FT's? The MAS Frequency In and Out is reading 59 to 64 Hz at idle and doesn't change when the O2's are going up. It only changes when I press the gas pedal. I saved the logged file - csv or in Excel format. If could only upload to for you to see what I'm talking about.
What are you using to tune? Do you have a logger? FT are Fuel trims.
You have 2 fuel trims. Short Term Fuel Trim (STFT) and Long Term Fuel Trim(LTFT).
Where are the percentages at?
I'm using a ECM piggyback (ECU+), but I haven't changed any of the fuel trims. Everything's set to zero.
I'll be getting new O2 sensor tomorrow and try replacing them to see if that makes a difference. I was told that the reading for the O2's, or the front one at least, should show the mixture from start - around 0.9's at start up. After two or three minutes it should go down to about .6-.7's or so. Maybe the O2 isn't good although it's giving me a reading. I'll let you guys know tomorrow when I have it installed.
Thanks for the help thus far. If anything else come to mind, please let me know. Thanks.
I'm using a ECM piggyback (ECU+), but I haven't changed any of the fuel trims. Everything's set to zero.
I'll be getting new O2 sensor tomorrow and try replacing them to see if that makes a difference. I was told that the reading for the O2's, or the front one at least, should show the mixture from start - around 0.9's at start up. After two or three minutes it should go down to about .6-.7's or so. Maybe the O2 isn't good although it's giving me a reading. I'll let you guys know tomorrow when I have it installed.
Thanks for the help thus far. If anything else come to mind, please let me know. Thanks.
Now that you mention this again, what exactly is your front O2 doing when you're idling or driving around in closed loop? It's *supposed* to be oscillating up and down, not sitting anywhere.
The FPR isn't stock but an aftermarket. I don't remember where the shop got it from or what brand, but it had cost about $30 on the bill (2 years ago).
I would take a serious look at your FPR, $30 is pretty cheap. I guy I know did a cheap ebay FPR chased tunability issues for two months and it turned out the regulator was being overrun causing a rich condition.
I changed the O2 sensors today and I'm still getting the same reading - from cold start at about .03 and after 2-3 minutes of idleing, it goes up to 1.00. The rear also reads that number after 5-6 minutes of idling.
As far as knock, I spliced the wires and I'm now receiving a voltage signal. No knock so far. Timing is showing around +23, give or take.
On the logger, my Injector pulse is around 5-6ms and the duty cycle around 4. I was told that this is to high and that it should be around 2-3ms pulse and 2 for duty cycle. I did another test to see if the ECU is working by pulling out a few sensors - O2, IAC, MAP, and even the MAF. The CEL never came on - no codes. I was also told that wiring is my problem. Do you think it's possibly the ECU going bad?
