Lean AF w/ Paxton !

[prevnine11ownr]

Hey guys...I have had great AF's for about a year (10,000 miles)...My readings were 11.0-11.5. Yesterday my AF's have jumped way lean !!! 13.-5ish (whoaaaaa). Any ideas what to do? Im going to change both paxton pumps for new ones.. Should i change the FCU? THANK GOD FOR AF GUAGES !!! John

 

[Fast Too]

Have you free air calibrated your wide band lately?

 

[prevnine11ownr]

NO i havent done that... How do u do that?

 

[Fast Too]

Do you have an LC-1, if so it should either have a button installed somewhere with an LCD light to do that, or if that wasn't installed you take the black ground wire from the controller and ground it for at least two seconds with the key on and it will go through its thing. Ideally you should remove the O2 sensor when doing this to expose it to free air. If 02 sensor is too difficult to get at you might let the car sit for a few days before doing the calibration.

 

[Kenny]

You may also have an O2 sensor that has gone south on you. I would test the AF using another meter (is there a local dyno) to establish if it is a legitimate problem with the car or a sensor issue. I would drive the car minimally/carefully until you establish that it is not running lean.

Have you noticed any changes in how the car is running?

 

[prevnine11ownr]

Car runs strong as hell...(but it would if it was lean).. I have the Western Motorsports wideband AF (got from Doug Levin).. Where should I start?

 

[Fast Too]

I would contact Doug for their free air cal proceedure, or search their (Western Motorsports) web site for it

 

[prevnine11ownr]

I have heard of these pumps (paxton) failing... Hell one of mine failed when it was new on Heffner's Dyno... He had a used one in his shop, so we replaced it...

 

[Fast Too]

very possible, I would start with the calibrating the 02 sensor if you have never calibrated it. Then move to the pumps and FMU

 

[prevnine11ownr]

I just checked...WMS widebands have an Internal calibration chip.. No external calibrations are needed. When you say calibrate the o2? What do you mean?

 

[Fast Too]

As it becomes dirty, it needs to sniff free air from time to time to know what 14:7 smells like so that it sends the right voltage signal to the gauge.

 

[Fast Too]

Do you have a link to their site, I keep trying to do search and when I click the links in the return results I keep getting page cannot be displayed......

 

[prevnine11ownr]

I just spoke to them...they said they gauge is probably correct. If it was the 02 they said the readings would be way off the map. HP Performance, Mustang Turbo Kits, Mustang Twin Turbo Kits, Corvette Turbo Kits, Corvette Twin Turbo Kits, C5 Turbo Kits, Z06 Turbo Kits, C6 Turbo Kits, C4 Turbo Kits, Acura NSX Turbo Kits, Grand Am Turbo Kits, Camaro Turbo Kits, Firebird Turbo Kits (must have changed names)

 

[Fast Too]

I guess its pump and FMU time..........good luck

 

[prevnine11ownr]

Thanks alot...least i caught it in time !!

 

[Fast Too]

having a A/F gauge is invaluable in a Paxton car

 

[Fast Too]

You might try PM'ing steponz. He may have a couple extra pumps and an FMU

 

[Kenny]

Disclaimer: I've troubleshot a more than a few fuel systems, but I don't have any experience with the Paxton setup on a Viper. There are people here more qualified than me to advise you on specifics.

That being said, I can tell you that changing parts as a shot in the dark can get expensive quickly. My advice is to do as much diagnostic as you can before you start swapping stuff and also change fuel filters and check all of your electrical connections---maybe something vibrated loose.

 

[Fast Too]

Disclaimer: I've troubleshot a more than a few fuel systems, but I don't have any experience with the Paxton setup on a Viper. There are people here more qualified than me to advise you on specifics.

That being said, I can tell you that changing parts as a shot in the dark can get expensive quickly. My advice is to do as much diagnostic as you can before you start swapping stuff and also change fuel filters and check all of your electrical connections---maybe something vibrated loose.

All true, just providing a possible source of parts at less than what paxton would charge if they are needed.

 

[GR8_ASP]

Do you have a fuel pressure gauge? I would start there before swapping parts. I find the fuel pressure easier to monitor when driving. Much steadier reading, no delay and real easy based on the increase when under boost.

Note I have close to 20000 miles on my Paxton. I have noticed a slight reduction in fuel pressure over time. About 5 percent. Not sure if it is actual loss or gauge drift but f/a readings have stayed about the same.

 

[prevnine11ownr]

yea, im going to check the fuel pressure tonite. Should be over 100 lbs at fuel boost.. I still am leary of the pumps for some reason.

 

[2002_Viper_GTS_ACR]

Couple of things, because I've been through the ticking time bomb known as Paxton and I still had one put on my second viper.

1st, there are some simple tests you can do to check this system out:

* Get on a dyno and while someone floors it (cant get that from free reving, needs to be under load), check to see that the fuel pumps kick on/get voltage. They ONLY kick on under boost, so they should read zero, and then under boost, voltage should jump to 12+ volts. CHECK BOTH.

* Next tap into the shrader valve with a pressure guage on the fuel rail and read the pressure. Make sure it goes to 100 psi under boost (again best done on a dyno).

* While at the dyno, most shops have those 02 readers, they arent the best in the world, but they will give you some type of sanity check against yours. Check that too and see if it also reads lean.

* Next Check your FMU disk, they are really easy to open up with 6 screws and make sure there is no binding of the spring or the diafram. Also make sure you have the 'richest' disk in there. Two are supplied with the paxton kit, its best to run the one that gives more fuel.

I ran lean and mean for a while and it made great power, and fortunately on this car no negative impact, but I put it to rich, so i could be safe. A few extra hp and faster 1/4 mile times doesnt mean as much to me as a strong, safe, reliable engine.

Hope that helps.

Jon

 

[prevnine11ownr]

We are on the same page... Im doing all of those tests currently !! Thanks John

 

[plumcrazy]

id get DLM on the phone before touching anything. if he installed it and tuned it, he should be called first.

 

[Doug Supercharged Vipers]

id get DLM on the phone before touching anything. if he installed it and tuned it, he should be called first.

Thanks Plum! Although I did not install or tune it - another tuner did. I'm just trying to help a Viper friend out

 

[Kenny]

Thanks Plum! Although I did not install or tune it - another tuner did. I'm just trying to help a Viper friend out

Plum I was gonna suggest the same think but then when I re-read one of the posts he mentioned Heffner's dyno in addition to mentioning DLM. I figured maybe he had bought some parts from DLM and then self-installed and tuned on Heffner's dyno.

 

[plumcrazy]

i tried........

 

[GR8_ASP]

A couple of things. One you have 2 pumps. One is on all the time. The second comes on when you are just about at a boost condition. When it first comes on it should increase the pressure to around 70 to 75 psi. As the rpms climb the boost should climb as well. Mine tops out just about 90 psi. How it climbs is based on the FMU and the actual pump output. Note I also run the rich FMU setup.

 

[prevnine11ownr]

Doug Levin (as always) has been a great help to me. I WILL NEVER take my viper to any other tuner in the future. Guys like Doug are hard to find these days. John

 

[Kenny]

Doug Levin (as always) has been a great help to me. I WILL NEVER take my viper to any other tuner in the future. Guys like Doug are hard to find these days. John

Did you solve the problem?