Car Bucking, Turbo Spiking... **HELP***

[Blitzeclips]

Hey guys I finally had the downpipe made and drove the car home last night from the shop. Everything ran fine out of the shop and to my home, but after we took it out to set my MBC, everything started acting wierd. For start, the car ran smooth into boost at first, no spikes nothing... Then, when I would be about 1/2 throttle in 2nd, and slam it, the turbo would spike HARD CORE, I would hit 8-9 psi, and get a bucking once or twice, let off the gas, and everything is normal again. The spike would come almost randomly, and the bucking would come anywhere after or before the spike (10psi).. At this point I'm thinking it's either

A) Vacuum hoses collapsing. This would be why the car ran fine from the shop (no heat) but when thing began cooking under the hood, the lines would either pinch or slowly slowy melt to a weaker state... This CANNOT Happen. Either the wastegate or FMU lines collasping will starve the motor of feul, both resulting in engine failure. I was thinking of using a feul hose at this point, I KNOW that feul hoses is much stronger then the silicone stuff..

B) Never set the boost controller, could explain the instant build in boost. But it doesn't seem so, the car was literally almost INSTANTLY shooting to 10 psi at the feather of my pedal...

Also, we came home to find the retu7rn line either melted or rubbed into my radiator, leaving a nice BB sized hole. Now I've gotta head to Pepboys and pick up a patch kit, hoping it will hold up to the heat rolleyes: ) and order a 90 degree barbed fitting to keep it 3" or so from my radiator..

See below, the pic shows where my return line is at the upper right corner. THATS where it's rubbing my radiator, and the hole was put.. http://i35.photobucket.com/albums/d162/blitzeclips/turbo install/turboinstallpics029.jpg



This little shit is getting old, but if you guys can help, please do so. I refuse to give up after going this far.. PLEASE HELP ASAP!!! I have work all week and no way to get there!!!

 

[4UH8ERS]

The bucking when the boost starts spiking sounds like fuel cut. Did you ever find out what that wastegate is set at or going to open at?

 

[Blitzeclips]

Its BELOW 8psi for sure... I was thinking the same thing but I have no missing link nor FCD... so I'm stumped at this point...


SOMEONE HELP!!!!!

 

[dr1665]

I have no missing link nor FCD...

! YOU NEED TO GET A FCD. You're getting fuel cut. Not sure why you didn't get it right off the bat, but you're describing fuel cut almost to a T. Time to pick up the missing link!

EDIT:
I know you're a 95, but if I were to describe fuel cut to someone, I would probably do so just like your post. Try easing into boost at speed. Roll along in second or something and progressively increase throttle input to build boost. If you are accelerating smoothly enough, you should be able to keep an eye on that boost gauge. If it cuts out as you cross into boost, it's cut.

 

[Blitzeclips]

! YOU NEED TO GET A FCD. You're getting fuel cut. Not sure why you didn't get it right off the bat, but you're describing fuel cut almost to a T. Time to pick up the missing link!

EDIT:
I know you're a 95, but if I were to describe fuel cut to someone, I would probably do so just like your post. Try easing into boost at speed. Roll along in second or something and progressively increase throttle input to build boost. If you are accelerating smoothly enough, you should be able to keep an eye on that boost gauge. If it cuts out as you cross into boost, it's cut.

Thanks Driggs. I appreciate the response.. Okay cool now we're getting somewhere... Okay, so worst comes to worst with the feul cut, will I be starving my motor and BOOM, or car shuts down (no BOOM) because it's thirsty? I need an idea of the WORST case scenario here.. If it risk blowing my block, I'm now building any boost until I get that FCD. JUst not worth the risk of my expensive block..

You are about head on with the boost characteristics. I find if I'm in a higher gear it will gradually build, but if I floor it, it litterally SHOOTS up and the car just goes.. The vacuum has a mind of it's own...


So, Where could I get an FCD or missing link, and for around how much? (I feel like a newb asking this),...

 

[DSMcrazy3]

So how come his 95 is the only ECU cutting fuel under low amounts of boost? Even though, like you said he's describing fuel cut...

 

[Blitzeclips]

So how come his 95 is the only ECU cutting fuel under low amounts of boost? Even though, like you said he's describing fuel cut...

Thats what I was wondering... I always thought an FCD or missing link wasn't needed for 95's???

 

[4UH8ERS]

what is the manufacture date in the door jam?

 

[Blitzeclips]

what is the manufacture date in the door jam?

Honestly I have no idea. I can check when I get home but there is one main harness for the ECU so I'm assuming it would be a 95... it's a 95.. though I can't say %100 sure of it..

 

[4UH8ERS]

ok you got the 1 plug ecu, then u should be fine. Reason I ask is because my car was made in november 1995 but its a 2plug ECU. I would suggest you evaluate your fuel sytem. (fmu, fuel pump, lines, injectors) because you explain fuel cut, and it may be coming elsewhere then from your MAP-->ECU.

unless your MAP sensor is faulty.

 

[DSMcrazy3]

unless your MAP sensor is faulty.

That's what my guess would be.

 

[Blitzeclips]

That's what my guess would be.

Pics to clarify where the MAP sensor is? I'm assuming the intake manifold, Most Absolute Pressure? I want to make sure I didn't tap into the sensor for a vacuum source...

EDIT: So should I buy an FCD or MAP sensor??

 

[XMasta19]

You don't need an FCD. MAP sensor is on the passenger side of the intake manifold, plugged into the top. You should give the FMU it's own vacuum source, but if anything tee it into your factory fpr line if you don't hook it up solo. I would verify all of this before buying anything, then would move onto a new MAP sensor

 

[DSMcrazy3]

This is the best pic I have for MAP location right now. It's on the far left side of the manifold, plugged in straight down. You can't miss it.

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You should not need a FCD or missing link since you have the 1 plug ECU. Like I said, I would put my money on the MAP being bad first.

Do you have SAFC or anything?

 

[Blitzeclips]

No, no SAFC or anything... decided not to use one until I do some tuning and up the boost later..

Yea my MAP sensor is still there, we def didn't use it for the vacuum source. My question now is about the stock FPR. We have the FMU hooked up solo, it wasn't teed into the AFPR... Would THAT be my problem? I couldn't see why though, the stock FPR would benefit me more with the FMU rather then without it...

Maybe I'm misunderstanding here...

 

[DSMcrazy3]

I think you are misunderstanding. To run under 8 psi your fuel system should consist of 12:1 FMU and Walbro 255 lph fuel pump, with stock injectors. You leave your stock FPR hooked up. I tee'd into my FPR line for my FMU and have had 0 problems.

Just because your MAP sensor is there doesn't mean it's functioning properly. Check the wiring near the EGR tube, make sure nothing has been burned through and or shorted out. If the wires are fine, consider replacing the MAP sensor itself.

Also, don't rule out the ECU. As we stated it's a 95, which of course are notorious for their spontanious failure.

 

[XMasta19]

+1 .... listen to the wiseman

 

[dr1665]

Hey. I don't suggest that I am incapable of error. Especially when it comes to the smiley face cars with boost. It definitely sounds like fuel cut to me, but it could be related to the regulator. :shrug With the ability to dip into boost gently, but not with snap throttle inputs, it could be hose related, but I really dunno at this point. I redirect to my boosted counterparts...

 

[Blitzeclips]

Okay guys littel update here. We replaced the vacuum lines with the high temp gas line... THAT s**t will NOT collapse... So, the spiking has gone down mildly, yet still continue to build rather quick... We fixed the radiator leak also... No cooling issues anymore.. I had quite the scare test driving it, because my coolant temp shot through the H! Luckily, some buddies reminded me to keep driving for cool air to pass, and the temp went back down. We went home, hooked up the rad. fan, and everything seems just fine now, well, as far as cooling is concerned..

The main problem at this point is my bucking again. Like I said, I CANNOT redline the car because my boost will shoot up, and the car will BUCK around 10psi.. So, I'm literally at about 1/2-3/4 throttle when building... I can't really get on it at all yet..


If anyone can also assist the bucking explination thatd be great. We are going to try some things with the way my FMU is hooked up, and see what happens..

Seems like the spike is primarily gone aftetr the line replacements, at this point the bucking is my main concern..

P.S- I made a little video for you guys with some buddies. No, it's not street racing either, so don't worry. When I get home from work maybe I can grab a chance to download before I head out tonite...

 

[4UH8ERS]

well your full system will not support 10psi your not getting enough fuel thats all there is to it.

push 7-8 psi and i bet your WOT bucking dissapears.

 

[Blitzeclips]

well your full system will not support 10psi your not getting enough fuel thats all there is to it.

push 7-8 psi and i bet your WOT bucking dissapears.

Oh I know this, but it's the bucking I'm concerned about. We have adjusted the boost controller but maybe not to 8spi..

So would the bucking occur because I may not have set the boost controller at 8psi? Therefore leaving my car to buiild constant boost, then buck after the injectors get maxxed out around 10psi? Sorry if that was confusing..

Hey, where's Paul at? I'm surprised he hasn't chimed in by now..

 

[DSMcrazy3]

The fuel system simply cannot supply enough fuel beyond 8, or roughly 9 psi when it consists of a 12:1 FMU and walbro 255. Period. The constant jump in boost, well that's just how fast the boost builds. Once the fuel system is maxxed out the car starts bucking. Get that wastegate regulated to 8psi. I'm nearly positive that the actuator itself is set for more than 8 psi so take the boost controller off for now so you can figure out what your wastegate actuator is set at. If you can't lower it to where you need it you will have to perform the wastegate mod.

 

[Blitzeclips]

I'll double check the wastegate, but I'm almost positive its below 8psi. I sent it to Chris for the wastegate mod, so it should be fine. I was thinking it was more along the lines of my boost controller being a problem...

So what is it like when you at oficially set at 8 psi? You build to 8 and it stays there? Allowing you to rev out the motor to redline without spiking or what?

That bucking scares the S-H-I-T out of me. When it bucks, is the motor being starved or trying to shut down before it gets starved? Like, will the motor BLOW UP if it bucks like that long enough??

 

[DSMcrazy3]

If your wastegate is surely set for less than 8 psi, take off your boost controller immediately, attatch a line from the compressor housing to the wastegate, and see how much boost you build. You shouldn't experience any bucking during that. Report back and let us know what the wastegate is set to once you actually boost.

When no bucking occurs yes, you will gradually build boost until about 3k rpm, then it will shoot up to where you have it set at and it should stay there until red line, depending on the turbo specs.

 

[XMasta19]

Yes yes yes...take off the boost controller now. You don't even know what your wastegate setting is??? You should have run with just the wastegate first, then moved onto adding the boost controller and slowly turning it up. For all you know you won't even need the thing. On the other hand it could be modded down to like 3psi, but at least you'll know. Then you can put the mbc back on and gradually work your way up to the fmu limits of ~8psi