[RESOLVED] Dramatic increase in pulse width after AFPR install

[turboglenn]

Well, even an experienced tuner needs some advice now and then so here's my situation

I recently installed an aeromotive AFPR on my car ( mods list in my profile)

I am running a walbro 255lph pump ( in tank). Well, since the AFPR install I've had to increase my pulse width a ton in the 6000 RPM + range at anything over 17 PSI.

I was running a PW of 6.081 at that load bar in particular and had steady aR's at around 11.2:1

Since the install and running a BFP of 43 ( with teh 1:1 rising rate FPR ) I've had to increase my PW at the same load bar to 8.01x to get from 13.2:1 back down to around 11.4:1. Thats' about 2 full ms.

My first thoughts are... And remember a few things. I am SPEED DENSITY, NOT MAF rating the airflow, just reading from an Acurate Wideband and programming a value. I have also tested the fuel pressure to over 80 PSi and there's no leaks or signs of teh pump starting to suffer. I have done a boost leak test and the leaks are too minimal to cause this in a speed density system, the car is jsut as drivable with a blown off IC pipe thanks to speed density

A.) With the 255 pump, my stock FPR was making much more than the 61psi that the rising rate reg would put out at 18 PSI due to it's small return hole size and inconsistancy of a cheap factory part

B.) My Fuel pump has started to fail since the AFPR install. This one doens't make much sence, but anything could happen. The pump only hold it's rpessure for about a minute after powering it off ( on a factory vehicle they should not leak down for almost overnight or 8 hours )

c.) The AFPR is just a junk unit and not making a true 1:1 rise through the boost range?


The first one doesn't make sense because these injectors are good for WAY more HP than what i'm pushing at those boost levels,

The pressure holding issue doesn't mean the pump isn't flowing right, it's just a pressure control valve/ one way valve / back flow prevention valve.. how ever you want to look at it. They commonly go bad on KIA's and hyundais, but the most common symptom is hard starting so i'm not that worried about that really either.

Either way, This isn't my first AFPR, i sold my last one being hard up for cash at the time. But since the install of this one, the AFPR has been inconsistant at idle settingsby 3-5 PSI, even after tefloning EVERYTHING down to the adjuster rod. So I'm starting to wonder the AFPR is making the amount of PSI that it needs to or not. At least the price of 255's these days are Sooo much better than what i paid at the time ( 8 years ago).

But i'm maxing out pulsewidth at just about at 18 PSI, and that's just not normal. I've run this pump and injectors alone for 6 years now with no troubles what so ever. it's been through both a stock and an AEM AFPR and has never faultered. So i'm confused, I'm asking for thoughts because i'm going to be trying to solve this issue on turkeyday without pissing off my family. Hopefully some one has had this same issue and can poitn me in teh best palce to look first.

And YES, i do have bad TB seals when performing a boost leak test, but everything else is solid enough to not cause this type of A/F ratio change

 

[turboglenn]

I guess if nothing else i will get it on the dyno as soon as i can ( probably friday if need be) and see if teh fuel pressure is dropping off in the higher RPM's and boost levels

 

[DSM90AWD]

I have an Aeromotive and found that the top adjustment screw/NPT boost fitting will leak if a thread sealant is not used. NOt sure if woudl cause you that much of an AFR impact, but definitely not going to maintain a 1:1 ratio. Also, are you using a dedicated boost source/line for the AFPR?

 

[turboglenn]

Yep, it has it's very own source of the manifold. Also put a ton of teflon tape on every fitting including the adjuster rod after seeing a quote from "oldman" on the subject. Even looking at maps i've exchanged with Sean Glazier of extreme motorsports, with his modded cars maps on 720's his was only about a half a pulsewidth more than what my car was tuned out to with teh stock FPR, in the same boost areas and on similar turbos. And i do have notes from him that his map was tuned on 42 PSI base Fuel pressure and similar mods to my car but a 60-1 and a little more free'd up intake system

I dont' get it, it's the pump or the FPR and i'm stumped, i'm thinking about either putting a long line to put the guage in the car if i can't get dyno time friday, or going back to the stock FPR and see if i run pig rich on teh new tune.

 

[architechnik]

What are you using to check the base pressure?
If you have a gauge on there at all times, they are known to be the cause of leaks sometimes while actually in motion. If you only installed the gauge for the check, possibly try using a different one.

With everything secured, it seems the vac/pressure line would be the only other common source, although you stated it was a direct from the mani.

Could it be somewhere in the install line? Hell, it could just be that the stocker with all the extra pressure and small return setup could have been WAY over pressure what it should have been.

 

[turboglenn]

What are you using to check the base pressure?
If you have a gauge on there at all times, they are known to be the cause of leaks sometimes while actually in motion. If you only installed the gauge for the check, possibly try using a different one.

With everything secured, it seems the vac/pressure line would be the only other common source, although you stated it was a direct from the mani.

Could it be somewhere in the install line? Hell, it could just be that the stocker with all the extra pressure and small return setup could have been WAY over pressure what it should have been.

I do havea a guage on a all times now.

And the thought of it just being the stock FPR holding back too much pressure was kind of dissmissed when sean noted that he was running an AFPR set at 42 ( vac line removed when set) and his pulse widths were only .400 over mine in the esame RPms and boost pressures... At this point, it's gotta be the pump or FPR...damn it, i don't want to send a brand new regualtor back, and i don't want to wait ona new pump, but it looks like it's going to be one of the 2. I was jsut hoping some one had this same issue and could say"this X reason, was what caused mine" i guess i'm just beinglazy about diagnosing it since it's the holidays and the family wouldn't be happy if i was at the hydraulic shop getting line and pulling datalogs half the day

 

[Talesin]

Well obviously your P/W is going to increase after an AFPR install if you were previously running it on the Walbro with a stock FPR. It overruns, fuel pressure comes up, injectors flow more at a lower pulse width. Switching to the Aeromotive (and properly setting your base fuel pressure) simply cleared up the overrun problem. Expected fuel pressure means the injectors are flowing less than they were when being overrun, so the duty cycle is going to go up to replace that 'lost' fuel.

As for the pressure holding issue, the stock Denso pump has an integral check valve. Walbros do not. The Aeromotive and AEM AFPRs are not designed to hold pressure in the system, and will slowly bleed down even with a stock Denso pump, meaning if you get hard-starting issues first thing in the morning, it's most likely due to the fuel all backing out of the lines into the tank, replaced with fuel vapor from the tank. I'm planning to try to fix my own problem with that by adding an in-line check valve just before the fuel rail.
In either case, did you remember to swap out for the proper-sized aperture/spring when you installed your AFPR? In the case of an Aeromotive, if the 'light' spring it ships installed with is left in place on a DSM, the pressure it provides is not sufficient to deliver a stable fuel pressure. If the return aperture is not sized correctly to the pump flow, either you end up with overrun (again), or an overly-sensitive adjustment screw (if the aperture is too large) and potentially 'twitchy' pressure again.

 

[turboglenn]

My whole install kit was from Import Revolution and is installed withall supplied fittngs and i have seen good reviews of it on here when i was searching and asking about one.

I didn't know the walbro didn't have that valve.. That's a relief. The more i think about it, I'm sure the fuel flow is falling off in teh top end. Wether it's from the pump or not i don't know. And i did put in the spring for the high pressure settings. I'm one of the old guys that reads teh instructions twice before proceding

The fuel maps from seans car that had an AFPR and highflow rail, were no where near as high as i'm having to run mine ( see above posts for info on those maps). and i'm sure his car was flowing more air than mine. something is definately wrong though, after more testing ( driving and watching the WB) i'm seeing that it will be fine at 5k at 18 psi but starts to fall off right around 6-6200 the lump in the map is a dead give away. I wish i could post a pic of the fuel curve, youd think i added nitrous from 6k RPM and up

At this point I'm thinking i'll get a new fuel filter tomorrow, put it on friday and get a line for an in car guage to monitor it friday if i can't get on the dyno to watch it.

I don't have to worry about the fuel backing out of the lines though, The haltech give a long enough "prime cycle" when the key is kicked on to where i've enver had trouble with that.

I just don't get it though.. AFPR or not, i have teh pump to produce teh fuel i need to not be at 84% DC at 6500 RPM and only 18 PSI when i've run into 28 PSI before on the same pump and feed line and had about the same duty cycle at over 450 HP as i'm hving now to put down around 360. And that was on an AEM rail and AEM AFPR

Sorry, this is frustrating me, i'm gonna sleep on it.

 

[turboglenn]

well, after more tuning the thing is not iimproving. The AFPR is still not holding pressure from one day to the next consistant'y and i'm still having to go 80%+ on pulse width starting at 5500 RPM and above.

HAS ANYONE, had a bad aeromotive AFPR from right out of the box?

I question it because the stock fpr will allow me to run my "old maps" jsut fine tuned well into the 20PSI + range and with this new one i can't hold fuel for anything above 6k RPM.

I haven't gotten on the dyno since they aren't open for the holidays, and the hydraulic line shop was closed keeping me from getting an in car guage on the fuel system.

I hate to waste money, but unless some one can back up my thoughts of a bad AFPR, i guess i'll be buying a new 255 and another new fuel filter ( i changed it less than 20k miles ago )

If it wasn't in the 20's i'd be more apt to go outside and wrench on it. But it's too cold to go to an unheated shop, and i'd have to move 5 motorcycles to another house just to get it in my garage here. at home

 

[architechnik]

All companies occasionally produce a faulty device. It's inevitable. While some have very high standards to prevent catastrophic failure (breaking) there are always the one-in-a-million probability that arises. Just the same for extraordinarily long lasting products from discount producers. It's all in probability.

Do not rule out that it is the FPR first thing. Do you have anyone that you could test it with? Have you tried attaching a pump to the manifold pressure line and check to see if the readout on your gauge rises with the changing pressure?

 

[turboglenn]

I need to get one that has "pressure out" the one i got from harbour freight only does vacum ( but i asked for it as a gift so i can't complain)

That would be the only thing i could think of that the AFPR would be doing to cause this. It's held steady at over 80PSI when turning the adjuster at idle, but that doesn't account for too much except proving there's no leaks and that the pump can put out pressure. I'm starting to really think i've lacking volume. I've made a TON of HP ( in my eyes for my setup anyway) on the stock filter an d it never came up short, and doens't on my stock FPR for some reason.

I hate the winters here, it will probably be freezing or below for at least 5 months from this point, so i'm none too motivated to get out there and start working. Once my metal shop is emptied out after the holidays, maybe i can park it in there and use teh goold old propane heater to make it warm enough to work. Arthritus at 30 y/o is a bi***, not to mention the knee and hip rebuids i've already gone through. It's the pain from those that brought me more onto the tuning side of things. I use to love pulling motors and trannies, but if just hurts too much these days. Even doing teh AFPR install in the high 60's was hard on my back ( the next parrt of me they want to rebuild from racing accidents )

 

[DSM90AWD]

A buddy of mine had problems with his Aeromotive AFPR due to his using the wrong style fitting at the AFPR that bottomed out and screwed up his pressures (he used a -6 flared fitting not the straight type).

Another thing that I have personally seen cause a similar issue was the fuel pump gasket having twisted on install into the hood causing a poor seal. Though you'd likely also have seen an increase in the time it took to get the car to start as FP would be slower to build

 

[turboglenn]

DSM90.. What gasket are you talking about? I put the stiff spring in before mounting the regulator if that's what you're talking about.

Fuel pressuree builds fast, as soon as i turn on the key it's up to spec. With it falling off at a certain RPM and above i'm starting o think the pump has seen teh end of it's lifespan. It's been ran hard through a stock regulator over the past several years. So, i'm ordering one and a new filter from Import Evolution on moday. THe pump i can change inside the car, so i'll just warm it up first. If it's still doing it i will force myself to take the pain meds, put on cover alls and chage that filter even if it is -15 outside

ANd as sure as i am about the pump, i still can't get it out of the back of my head why it would have just shown up on the NEW regulator and never on the other one.. But, i can't see ANY way this regulator could fall off spec dependant on RPM ( not possible for teh FPR to sense RPM derr ). I can build 18 PSI at just about 4k in 3rd gear starting by rolling on it early from around 2k.. and the pressures and pulsewidths are fine untill the PRM'g get much about 5000

I guess if a new pump and filter don't solve it i'll ask IE if they will swap me out for a new unit. BTW, the fitting on the bottom of mine is the one supplied with the kit, so i'll take with reguard to people who've bought it, that it's a good setup right out of the box.

The 225 walbro is only 90 bucks these days WOW! when i bought it they were going for around 200+.. if there any other good pumps in the lower ranges these days or should stick with the tried and proven walbro 255?

 

[turboglenn]

Well, i just proved the regulator good. I used my tiny track compressor with the air blow on it and put a vacum line on the AFPR's vacum/boost nipple.. I was able to raise and constantly hold higher pressures with pressure on the nipple.. although i couldn't tell if it was truely 1:1 since the small compressors guage doesnt go below 30 or so when you let all teh air out of it.

I just changed to batch fire injection a few minutes ago instead of multipoint to check another varriable. This way i'll see if it is maybe coming from too large a pulsation in the factory rail. But i don't see why the mitsu rail wouldn't keep up at such low power requirements. (tuning in the 17-18 psi range while this is happening ) I've had it well beyond there before.

 

[Talesin]

I'd just stick with the 255-HP.
Okay, so the AFPR is good, no problem with the rising rate adjustment there. Meaning the pump may be suspect. Might be silly to ask, but have you done the rewire? Is your alternator putting out enough juice?
It's running okay on the stock FPR because the FPR is being overrun. Though it shouldn't be a problem when the flow is being taken up at the high end of the range. Hmm.

Easiest way to check it would be to do a pull on a dyno, and have someone watch your fuel pressure gauge. Though at this point I'd say that it may just be something with how the car is tuned... possibly something in the EMS isn't playing nice, and it's a tuning problem rather than a mechanical issue.

 

[turboglenn]

I've ruled out tuning. I've been on this system too many years ( and use to be a dealer ) so i have all the factory support PDF's,notes on problems and patches and tests.. The ECU is checking out fine.. The last time i saw this was on a 88 RX-7 turbo II i did where teh 190 pump coudn't keep up in the top (eventhough pulswidth is near the same at one particular load/boost in most RPM's, they're firing more often up top) and probably running my "In" line low on volume/pressure

If i can't get on teh dyno tomorrow, im going to throw on a fresh filter and test that untill i either get a pump or dyno time.

And no, i haven't done teh re-wire. I figured i didn't really need it on such a large pump. But the more i think about current draw and Ohm's law, the more i think it may help to do anyway. Usually we run new wires on larger external pumps, but have always kept stock wiring on in tank units (except the WRX sti with it's variable pump voltage system)

My alternator is good...data screen on the haltech shows 13.6 - 13.8v with minimal accesories on

BTW,, Do you know what model VW to ask for to get the bosch LSu4 sensor? I don't feel like waiting on the mail during the holidays so i'll pay a little more to get it locally. but the parts guys around here can't figure stuff out without an exact application anymore ( minimum wage being teh culprit i'm sure )

 

[Talesin]

Yeah, the larger pumps really suffer (and the stock pump does too, actually) from the stock wiring. If you run the car and turn on a turn signal, you can hear the pitch of the whine change as the light blinks. Which is kind of ridiculous.

There are notes/tables on pump flow up on VFAQ... short version, even rewiring the stock pump gives you MUCH stronger and more consistant flow. With a Walbro, they're designed to operate at 14V, and suffer when they get less. Doing the rewire isn't too difficult, and even moreso on a car where the battery has been relocated to the trunk... good for AWD, not so good for FWD. Stock location isn't too difficult either though, just have to run ten more feet of wire or so.

Check your alt at the B+ terminal (the big bolt that all the wires are clamped down to, not the plastic push-connector). Even for a crappy Autozone alt, the minimum charging rate for a 'good' alt with *all* accessories on at max (interior fan, radiator fan, AC fan, headlights on high, dome lights and map lights on, cigarette lighter heating, stock-ish stereo up loud) is 13.5V. Not the initial drop when a new accessory starts adding load, but a few seconds later it should pop back up. Apparently a 'perfect' Autozone alt is putting out 14.7V under those conditions, since our alts are internally regulated. It shouldn't deviate far from that. And if the alt consistantly goes under 13.5V where they can test it on the car and see, they honor their lifetime warranty.

Sorry, don't even know what the LSu4 sensor is, don't use it on my current setup and this is the first time I've heard of it referred to in that manner.

On a side note, our fuel filters very rarely go bad or clog. From what I can see, it looks like they're based on an older, very solid Toyota design. I replaced mine last year and found out that the one on the car was still the stock one from 1990. Adding on the new filter got me roughly an extra mile per gallon or so, but I saw no real increase in WOT performance.

 

[turboglenn]

I'm goinng over to the shop to do a Fuel pump re-wire and change teh filter for the hell of it. I'll pull some logs and have the wideband in making sure of what's going on. I'll update when i get home tonight.

 

[turboglenn]

Well, it's fixed! I re-wired the fuel pump with 12 guage wire straight from the battery, witha 20 amp fuse and a 30 amp relay. I also changed the filter for the hell of it since i had the battery tray out and had bought the filter. The old one didn't seem clogged at all.

I took it out on teh road with the wideband and haltech/laptop riding shotgun. The wideband immediately pegged at 9:1 under any boost what so ever, i spent a few minutes dialing in the maps before i called it a night, and it was doing what it should. At the same pulsewidth the 4.5k-5000RPM areas were at 11.2:1 and when it got in the high RPM's it got richer at the same pulse width,which it should because there's less VE at the higher end of the particular motor and cam setup. Mainly when you run past the area where you make peak HP.

Thank God! i got it done in a warm garage and got some turkey left overs and a car that's running in top shape again. Thanks for the info on the re-wire Talesin

 

[Talesin]

Excellent! Glad you got it sorted.