causes of a car bucking?

[TweeT91109]

Ok so, recently fixed a messed up CPS...and had a miss fire....well cleared that all up...and motor is running good. So im crusing over a long bridge last night, and its just me...so I get on it, and I mean get on it. All is fine, I get off the bridge, and the interstate, and come to a red light....everything is idleing fine, so its ok....well I go to leave the red, and kinnda get on it, I hit about 3-4k rpms, and the car seems like its hitting a fuel cut? It just cuts in and out...and this is in all gears. It just gains rpms, then starts bucking, and its kinda violent. So today I checked for a boost leak, and fond nothing....any one have any other ideas? Thanks to all

 

[gamer565]

Whats your boost psi at?

Any mods?

 

[whitemike]

I would have to say It's your timing. I had the issue a few days ago when I was messing with my timing, but it all got situated, and the rocking/bucking is gone..

Also you gotta stick with the rule of, 'what did I fuck with right before the problem started' ..

-Mike

 

[TweeT91109]

Ok so I took apart all of the intercooler piping today, found a few lose clamps but nothing to cause a difference. Put it all back togeher and still doing the same thing...Over on Supraforums, they suggested the AFR's so im, thinking of getting a AEM wideband. Both to monitor the ratios, and bypass the 20 yr old stock connector. Will let you guys know what happens, as soon as I do.

 

[IBoughtASupra]

Bypass a 20 year old connector? What do you mean? If you are talking about the stock 02 sensor, leave it in there. If you want to do anything, replace it with a new one but don't remove it. The ECU won't know the fuel mixture.

 

[TweeT91109]

Bypass a 20 year old connector? What do you mean? If you are talking about the stock 02 sensor, leave it in there. If you want to do anything, replace it with a new one but don't remove it. The ECU won't know the fuel mixture.

I could do this...my elbow has 2 seprate bungs....so I think I may use them both....

 

[88t]

I could do this...my elbow has 2 seprate bungs....so I think I may use them both....

You should do that unless your running a standalone ecu. Running a wideband on a stock ecu is just like running a aftermarket boost guage. It's just an extra guage nothing to do with the stock o2 sensor. If that made since

 

[TweeT91109]

Yea it did....but the only reason I would do it like I said, is to check out the AFR's. Cause thats what im thinking is making the car buck on WOT.

 

[whitemike]

Did you read my suggestion?

 

[stolensupra]

Try Checking for a small high pressure only boost leak between the intake manifold and the vacuum brake booster on the inner side of the hose. I had a similar situation that caused boost spikes.

 

[TweeT91109]

So I was looking at my boost meter today...and its boosting to 12 lbs. then it cuts out. It usually only runs to 10 and maxs out....which it was I thought I had it set to. So im guessing its hitting fuel cut. If im wrong please let me know. And if anyone knows how solve this problem, please let me in on this info.

 

[stolensupra]

Technically you can raise your fuel cut just a smidgeon by expanding the size of the area that permits unmetered air to flow through your afm housing. On the metal part there is a distinct place on the bottom corner where it seems there is an aluminum plug. when you take the unit off the car and take out the air filter and the afm you can see it protruding through. Take a 3/8 or so (double check this) drill bit and drill out the very center of the plug. Once you get this drilled out you can; 1. use a screw extractor such as micro grab-bit and reverse the drill direction to pull the plug out 2. just keep ever expanding your drill bit size until you can fully seat a flat head screwdriver and extract the unmetered air screw. Be careful to not drill the screw head as it will distort and you'll have to use the extractor on the screw itself. You can let it sit loosely by the rubber grommet that is in there but you risk losing it under high vibration. I just put some metal based epoxy putty in the tip of the hole so i could easily drill it back out and re insert the screw if necessary. Whew that was a mouthful. Hope this helps bro.

 

[IJ.]

Flanking strap too tight?

 

[TweeT91109]

Flanking strap too tight?

What is a flanking strap ?

---------- Post added at 08:39 PM ---------- Previous post was at 08:37 PM ----------

Technically you can raise your fuel cut just a smidgeon by expanding the size of the area that permits unmetered air to flow through your afm housing. On the metal part there is a distinct place on the bottom corner where it seems there is an aluminum plug. when you take the unit off the car and take out the air filter and the afm you can see it protruding through. Take a 3/8 or so (double check this) drill bit and drill out the very center of the plug. Once you get this drilled out you can; 1. use a screw extractor such as micro grab-bit and reverse the drill direction to pull the plug out 2. just keep ever expanding your drill bit size until you can fully seat a flat head screwdriver and extract the unmetered air screw. Be careful to not drill the screw head as it will distort and you'll have to use the extractor on the screw itself. You can let it sit loosely by the rubber grommet that is in there but you risk losing it under high vibration. I just put some metal based epoxy putty in the tip of the hole so i could easily drill it back out and re insert the screw if necessary. Whew that was a mouthful. Hope this helps bro.

And im trying to not mod the car any further....cause the currents ones have been proven to work...and thats what im trying to get too....

But, I was messing with a boost controller today, and it is still spiking. So im moving to the next thing (which I have no idea what it is yet).

 

[TweeT91109]

So I went to work on the turbo, and intercooler piping...found a few pieces that could use replacing...but nothing major. The rubber line that is connected to the turbo acuator (manual boost controller lines) looked like they really needed to be replaced...so I did. And the car is still hitting fuel cut. And I have tried setting it to both the max and lowest settings possible, just in case I got them confused. But no, its still hitting the fuel cut. So im still at a loss, maybe a tune would help, and how would I go about getting one, becasue I have read the 7m ECU, isnt tune-able