WOT bucking

[desert_gypsy]

A few weeks ago, my FRPS went out and subsequently caused a fuel pressure spike which blew one of the Gates fuel lines off of one of my pumps. Got that all resolved and the car ran great (Thanks to Greg and the guys at RET for their help on this issue). Another week or two later, I changed the oil and cleaned/re-oiled the air filter, and the car ran great all the way to Vegas (there may or may not have been some felony speeds attained on that trip). The car ran great at WOT until just the other day. She seems like she's losing fuel in 3rd at WOT at about 3-4krpm (I'm not certain since I don't stare at the tach). It feels like the bucking you would feel due to the PPRV between shifts, but it only does it in gear under heavy load. I've read up a bit, and I've come to 3 possible conclusions.

1)Spark plugs. TR7IX's with about 5k miles on them, gapped at .032. I think spark blowout would feel more like a flutter or some slight hesitation, though.

2)Oil from freshly oiled air filter on MAF element. I think this is a possibility, but would likely be noticeable at part throttle as well.

3)Damaged FPDM due to fuel pressure spikes caused a month or two ago by the bad FRPS. It seems strange that damage to the FPDM would rear its head months down the road, but still a possibility in my mind.

Any input on my ordeal is, as always, greatly appreciated. :beer:

 

[MissionMan]

im putting money on #2, i think you can clean the maf with a q-tip and isoalcohol

thats the first thing i saw in your paragraph was "re-oiled air filter".

 

[desert_gypsy]

ttt

 

[desert_gypsy]

Just noticed this morning that the car is getting harder to start. I have to crank it a bit longer than usual (even after the PPRV delete) and sometimes she barely shudders to life. Feels like a fuel problem (again). This makes me lean more towards the damaged FPDM as the culprit. Comments/suggestions?

 

[sc98cbra]

I had the same issue with my Redfire...

*Try changing the belt, Might be belt slip.

Also, with the PPRV delete, you will need to let the fuel pumps fully turn on before cranking the car. If you don't it will damage your FPRS, which also may be your issue...

So you might want to also invest in a KB FRPS disc.

I know it may be a waste of money, but they cost like $15 for a belt, and like $30 for the KB FRPS disc, and will eliminate those two things, or could possibly fix your problem

Hope I read your issue correctly (Its 4 A.M, and I've had no sleep since 5AM yesterday), and I hope I responded correspondingly to your issue. LOL

 

[desert_gypsy]

haha, thanks bro. I've got a new Gatorback belt on the way (hopefully I bought the right size lol) and some belt dressing. Just got my FRPD from KB in the mail today (err, yesterday) and I'm gonna pull the MAF this weekend and give it a good cleaning. I think I actually have a spare MAF in the garage somewhere, too. I'm hoping it's not the FPDM because I'm headed to Vegas again next weekend and I wanna tear up the backroads on the way. With any luck, the new belt and clean MAF will alleviate my problem.

 

[04cobra13]

id get the tune checked out if its not any of the above.. By the way did u recently delete the pprv? Only asking because my car did the same thing after i deleted it had to be retuned..

 

[DocButters]

Fix it?

 

[desert_gypsy]

id get the tune checked out if its not any of the above.. By the way did u recently delete the pprv? Only asking because my car did the same thing after i deleted it had to be retuned..

Yeah, I deleted the PPRV a couple months ago, but the car ran fine for weeks, up until I blew the FRPS. Replaced FRPS and the car ran fine again. I don't think this is a tuning issue, as nothing had been changed when the car started to act funny again. I could be completely wrong on this, too. I still need to check my MAF and see if there's anything wrong with it. The alternator also crossed my mind, but I think I'd still have enough juice in the battery to get a strong spark at WOT, especially seeing as the BAT light isn't on. Anyone have any other ideas/recommendations?

edit: btw doc, good job on getting banned be safe, boot. lol

 

[xavier296]

Check the plugs first!!! Sorry if I missed it, but I don't think you said you checked them. My brothers 03 had one bad spark plug, and he replaced everything before figuring it out. It was only causing problems at WOT and high loads and would stutter and do strange things. It was one 2 buck spark plug causing everything!

 

[xenodragon]

1. Clean the MAF with a spray of brake cleaner

2. The PPRV tends to cause alot of other problems. The start up issue is most likely due to the PPRV delete.

3. Dont really know why the FPDM would go bad. I mean its just a control module isnt it? The fuel spikes whether big or small shouldnt exactly break the FPDM.

 

[desert_gypsy]

UPDATE

Just got my SCT X3 in the mail and only had to look at the thing for a matter of seconds to help tremendously with the diagnosis. These things are worth their weight in salt when it comes to troubleshooting newer cars. Anyhow, I checked my FPDC and it's peaking at .50.... not good. It's either a dead pump or bad FPDM or a wiring issue. I'm assuming somebody knows exactly what my problem is. I'm just not sure how the FPDC is calculated; a signal straight from the FPDM, or a cumulative signal from the pumps themselves. Any thoughts?

 

[desert_gypsy]

Ok, so I just realized that I'm supposed to multiply the FPDC signal by two. That adds an obstruction in the line as a possibility. Maybe a kink as those Gates lines are a PITA to orient around the pumps.