LaXGSR

Hey all, so recently something very disturbing happened. I didn't know it, but my FPR hose had popped off, which should make the car run VERY lean (up to 15:1 afr according to some people).

However, my car did not knock at all. I did multiple WOT pulls, logging the car at nearly 25 psi peak, and there was no knock. Shouldn't the car knock if running lean? The only symptoms I had was that the car would hesitate and jerk a couple times as it hit peak boost. Logs for timing/boost looked fine.

Even more disturbing is that when I switched to the stock map (using tephraXMOD), the car did not jerk at all. It ran perfectly smooth as if nothing were wrong. Presumably, it was running lean though.

I was just surprised the car did not knock even with the FPR hose popped off. Maybe I need to permanently install my wideband to monitor AFR's. I thought I was safe enough with the knockCEL. Btw, my car is stock except for the tune. Could I have caused some permanent damage doing 10 WOT pulls?

Golden

iTrader: (1)

You were probably running pretty rich before.

LaXGSR

I logged afr about a month ago and was running 11.1 afr tuned. I'm pretty sure it was lean without the fpr hose since the car did hesitate noticeably a couple times at peak boost.

SilverEvoX

iTrader: (2)

Why would you deliberately run WOT if you knew the FPR hose was disconnected...are you trying to blow the motor? You could definitely cause major damage if you were doing WOT pulls like that with AFR's in the 15-16:1 range.

What year is the Evo so we know how rich it was from the factory in the first place? 2010 is a full point leaner than 2008 in most cases.

What fuel were you running? If you have alt maps I'd assume something other than pump gas

I saw as high as low 16:1 AFR's when mine blew off on my wideband and you can feel the car go lean, it's like hitting a brick wall when it starts to lean out. Either it didn't pop all the way off at first during those pulls and was still sorta on getting a reading from the FPR or something else entirely. Are you sure you have the correct knock definitions in your tune so that the knock light is functioning properly?

I'd guarantee you were knocking a ton if it blew off and you kept doing WOT pulls. At anything over about 13:1 you will feel the car go lean and start pulling timing if you're running pump gas, it's unmistakeable. Even if you were at 10:1 before hand so on the rich side it would have still been probably 13.5+ AFR and been pulling timing/boost.

Definitely install a wideband so it's visible, it's a cheap safeguard. Do you have what the AFR's were during these pulls if you were logging?

maxima92se

I'm confused so you knew the hose was popped off? And I'm not 100% sure what your car entail but my maxima was a little loud so I wasn't bake to hear the knocking except the car would hesitate and I my wideband sensor was out so therefore kaboom before I knew it.

LaXGSR

2008 stock rom ran 10.5 afr on my car. i didn't know the hose had popped off so i was datalogging wot pulls with evoscan. the car felt fine except for the couple times of hesitation at peak boost. running 91 oct at high elevation so its a little less knock prone.

btw unforuntately did not have wideband in during those pulls so thats why im so worried. thought it was a boost issue at first. did not reali2 fpr hose came off. running my tuned map with stock rom as the alt map. also knockcel def works as it will flash occasionally after a while of lapping on the track.

SilverEvoX

iTrader: (2)

You should have definitely been able to feel the car lose a ton of power as soon as the FPR hose popped off. Seriously, it's like the car losing 150hp...when it leans out that bad. Also after the FPR hose pops off the car idles at like 2k rpm.

If you didn't feel this and the car felt fine, then most likely I'm betting the FPR hose blew off sometime after these WOT pulls because you would have noticed the loss of power, the car completely falls on its face when the FPR hose blows off. Maybe the tuned pulls loosened it and the regular driving afterwards caused it to come the rest of the way off. If you haven't already, put a zip tie on that bad boy where it connects to the manifold to prevent further popping off.

If it's driving fine now, not knocking, and still pulling strong then its probably fine. However if it's running like crap now I'd definitely do a compression test and keep your fingers crossed that you weren't actually doing the pulls with the hose popped off.

LaXGSR

thanks i didnt feel a loss of power and the car idled normal...weird. after reconnecting the hose and using both hairspray and a hose clamp, that stupid hose is stuck on pretty tight now. car drives normal and hesitation is gone. no knocking either. its scary that on the stock tune there were no noticeable symptoms. im pretty sure that hesitation was because the hose was off, since putting it back on fixed it.

cornercarver

iTrader: (4)

This very same thing happened to me the other day. Though my hose was not completely off until the last pull where I finally threw a code p0171 (system too lean). During these issues, the ECU will add around 12% more fuel to compensate. If that is overwhelmed, it will throw a code. If you didn't throw a code, then it was able to compensate for the most part to keep the engine safe.

My AFR's were in the 16's at peak torque and I saw ZERO knock. This was on 91. Plugs were fine and she is still running great. I doubt I have any cataclysmic damage like it was described above.

starks

I think some of us may be jumping to conclusions about the probability of damage here. I had problems with hesitation for the past week and a half. I checked everything and was convinced it was my maf. I finally stumbled upon another thread today and realized it was the FPR which was completely detached.

When I was first diagnosing the problem I did multiple runs that showed no knock what so ever. My problem even decreased somewhat when I switched back to my perrin filter and stage 2 map, again without any knock. Granted I wasnt doing tons full rev range wot, but I was always checking to see if the problem had gone away by going wot 3k to 4k. Plus I drove 1000 miles total for a beach trip with a few occasional low gear rips. Today, when I found the problem and retested the car. everything is feels 100% ok again.

Of course I didnt realize how much power I had lost cuz the car pulls like the devil again! Maybe some timing got pulled along with the extra 12% fuel. I highly doubt I was running 15 or 16 to 1 wot though. Seeing as so many people have had the problem with no real horror stories, I'm sure most people are completely fine after replacing it.

SilverEvoX

iTrader: (2)

I just don't understand how several of yall could be driving around and not notice it being off...the car idles at literally almost 2000rpm when the hose is disconnected. When you try and go WOT you can feel the car lose tons of power and see the AFR spike lean on a wideband instantly. You can doubt that you were running that lean but I've confirmed it with my wideband when it happened as well as several others have seen this on their wideband when the hose popped off. I guess it comes down to how rich it was tuned in the first place but when I was set to 11.5 AFR it went to 16:1.

LaXGSR

Thanks for all the input. It sounds like a lot of people, especially on stock tune, don't notice a loss in power (especially when reading about all the people that didn't know their hose had popped off in the main thread on this issue). I did not notice a weird idle on my car when the hose was off (maybe slightly high, around 1000-1100 rpm's, but nothing crazy).

I don't really want to test how lean it was, but maybe it would be worth doing a partial WOT pull while closely watching the wideband with the FPR hose off, just to get additional data. I did not notice a huge power loss, and it pulled nice and smooth even without the hose, which is SCARY. No Knock either...I wish I had my wideband installed at the time...

starks

Well I definitely noticed a problem, but attributed it to maf since I had a reason for it to be bad. My idle wasnt that crazy, it just dropped from 1000 to 500 and then back ina very lumpy fashion. Again no knock is what made me feel secure. Glad I know now of course and wouldn't let it happen again. What's everybody s thoughts on method to secure it?

LaXGSR

I tried a zip tie, but I could still easily pull it off. So I got a fuel injection hose clamp (that came in a variety pack from autozone) to secure it, and it was a little better, but still too loose for my comfort. Finally I put a bit of non-aerosol hairspray on a paper towel, and dabbed the metal piece with it before putting the hose on. Then I let it sit overnight, and now it's pretty tight (can't easily tug it off). I am periodically checking on it (tugging intentionally) to make sure it's secure.