SEVERE BUCKING under load!

[Foreverfalcon40]

Orignally it happened around 4,000 RPM's in 2nd gear. The it went away, and came back.
What could it be?

I can't be a bad injecoters, nor plugs, maf, or even injecoter wiring.
Cam sensor?
Timing Belt (missing a tooth)?
My BOV is currently venting, but I do have a 1g BOV in the mail this week via EBAY. But I don't think this could be the only cause.
Also, I have no boost controller on the car and I my boost gauge reads 10psi. I assume I have no leaks but instead some creeping. I think this is caused by my stock 02 housing being bolted up to my ported 16g with full 3in exhaust?

If it is the cam sensor, I heard it is a pain to install. If installed wrong you can screw up your whole motor. I am a do- it yourself guy, but if thats the case, off to the mechanic I go. I would not be surpised it could be the sensor due to the fact prior to purchase it had no hood on so the elments of wheather such as rain could have ruined it.

 

[luvmygst]

What kind of boost gauge do you have? People have a hard time keeping a ported 16g at 10psi without porting the o2 housing especially with 3" exhaust.

 

[EclipseTrbo420A]

I had this problem and damn if is wasnt as simple as my plugs. NGKBpR7es's gapped at .028 did the trick

 

[romeen]

Start with the basics.

1) Check your plugs as Matt stated. Excessive gap can cause misfire under load. Also make sure your plug gaskets for the valve cover aren't leaking allowing oil into the plug wells. Make sure the plug wires are in good shape.

2) Boost leak test.

3) As you know venting your BOV is not good but I don't know that it would cause the problems you are describing. Glad to hear that you will be taking care of that this week.

If these check out then move on to other less frequently occuring possibilities.

 

[Foreverfalcon40]

It can't be the spark plugs, they are all gapped .28 and they are NGk's. I bought the plug wires used and they did have some oxidation (lloks like rust) on them. The type of boost gauge I have is a Autometer Cobalt Series Boost Gauges which reads from 0-60 psi. How can I tell if the there is no oil leaking into the Spark Plugs? Remove all the spark plugs? If that is the case, would I use one of those squeezey ball syphosn to get the oil out? Of course an immediate change of valve cover gasket will do.

 

[romeen]

To check for oil in the well just remove the wires and shine a light down the well. There would also be oil around the thread of the spark plug. If there is oil hopefully there wouldn't be so much that you would have to siphon it out. But if you have access to a gun cleaning kit you can just attach the cotton cloths to the tip of the wand that you would normally clean the barrel of the gun with. It will reach down there and the cloth is secure.

 

[tsiboostin]

I had a probelem similiar to this when I first got my talon. Once I would get aroun 7lbs of boost it would buck like crazy. After checking a ton of things I finally discovered that the gas tank had rust from the prev. owner leaving gas it in for years while it was in the garage. This clogged the fuel pump filter and made my car lean out. Just a suggestion I'd say give it a look.

 

[romeen]

I had a probelem similiar to this when I first got my talon. Once I would get aroun 7lbs of boost it would buck like crazy. After checking a ton of things I finally discovered that the gas tank had rust from the prev. owner leaving gas it in for years while it was in the garage. This clogged the fuel pump filter and made my car lean out. Just a suggestion I'd say give it a look.

That's actually a good point. But getting timing pulled due to running lean has a different feel to it, kind of like short rapid bursts of acceleration/deceleration. At least that is what I have experienced. The bucking during acceleration is most commonly caused by either a boost leak or misfire although I'm sure there are other less common causes. Again this is just in my experience.

 

[Foreverfalcon40]

How could there be a boost leak when I am pushing 10psi w/o a controller of any sort? I ordered new wires yesterdayb/c I know my current wires looks like its rust on the metal parts. From there I will check the plugs...Still waiting on my BOV. Remind that this problem occurs out 80-85% of the time while under load. It's consistent though and N/A under normal driving conditions.

http://cgi.ebay.com/ebaymotors/ws/e...RK:MEWN:IT&viewitem=&item=230109006712&rd=1,1

 

[romeen]

If your current wires have rust on them then hopefully the new ones will solve the problem although I am not familiar with the ones you bought.

Just because you are running only 10 psi does not exclude the possibility of a boost leak. How can you be sure that you are only able to run 10 psi because of a boost leak? The ONLY WAY to ever be sure that you don't have a boost leak is by doing a leak test.

 

[Foreverfalcon40]

It's not rust but it looks like it...I think its called ionization?

 

[romeen]

If it looks burnt then it could be from arcing which might explain the problem.

 

[Foreverfalcon40]

I was reading about arching briefly while in class and I just did it before. Now they say to fix it with JB welb which I will never do. Now the descritpion and pics are quite difffernt. Is arching take place where the metal tube is inisde the rubber? ### the show a pick of the rubber being spliced opened and resealed with JB weld.

 

[romeen]

Typically arcing will be at the same level as the end of the plug connector inside the plug boot. Here is some info from Magnecor's site which might help. About half way down the page they talk about arcing.

http://www.magnecor.com/magnecor1/techbulletins/tech_mrbishi1.htm

 

[Foreverfalcon40]

Ok, so I pulled my plugs when I got home from school. It was dark out so all I did was just pull the plugs and feel for oil one them. I didn't find any but when I pulled a spark plug wire out the metal part inside the rubbber stayed on the spark plug! Could this be my problem?

 

[romeen]

That could definitely be the problem. If the wire has been broken where it meets the connector then the conducting portion may still be in contact with the connector enough to allow current to pass through to the plug most of the time. But at other times vibrations may momentarily break the connection causing no spark in that cylinder. Only way you will know for sure is when you put the new wires on.

 

[Foreverfalcon40]

Ok, here's the update. I had no time to touch the car b/w school and work. But I am driving it around town, this is my first stick car. This post was constructed on those accounts when I am the passenger and my friends from the mechanic shop drove it home amongst other test drives.

Now: I realized once I start the car and the engine is not warmed up, under load it doesn'tloose power. But once it warms up and comes under light acceleration is starts to break up between 3krpms and 4krpms in all gears. But if I just accelerate very lightly then it will drive fine. Could this be severe heat soak or boost leak?

 

[EclipseTrbo420A]

Replace the wires and the plugs..gap them to .028 If you dont know how just ask. Thats what I would do first...its always good to do no matter what, so your not losing anything. Goodluck.

By the way boost leak would buck all the time and heat soak would be after 2 maybe 3 HARD pulls...with no bucking or anything ya know ?

 

[awild]

Was this resolved? I've got the same issue on a 98GST I just purchased. Sucker blew the recirc hose off and I unknowingly drove it a few miles like that. Probably fried a plug. She's bucking like crazy above 3k rpms.

Looks like it might be a cold spark plug change out tomorrow.

 

[always_broken]

Check you front 02 sensor. You could be running rich as crap. You have any logs?

 

[awild]

Check you front 02 sensor. You could be running rich as crap. You have any logs?

No, just bough the car the other day. I have a daily driver Jeep so it's no huge rush. I'm going to check the plugs tomorrow pending weather.

As far as checking the front o2...what am i looking for?

 

[always_broken]

Well you'd throw a cell if the front o2 was malfunctioning. But you'd check the voltage at warm up and see if what it reads. 0.01 is lean and 1.0v is rich. Better to have a logger of some sort because that's one of the things you can see how it's operating.

 

[awild]

Well you'd throw a cell if the front o2 was malfunctioning. But you'd check the voltage at warm up and see if what it reads. 0.01 is lean and 1.0v is rich. Better to have a logger of some sort because that's one of the things you can see how it's operating.

Is that something autozone could read until I get a logger? If not I'll see if I can't get a logger setup soon.

 

[awild]

My issue was solved with new spark plugs. NGK 6's replaced some older split top torched to the max ngk's. Gapped at .028 and didnt get it to hesitate or buck. I'll have to take it for another drive tomorrow and let it warm up to make sure. Best $15 in parts and tools I've ever spent.

 

[96gstdsm]

Spark plugs could be your problem. Also perform a boost leak test even if you don't think you have one. Also check your TPS to make sure it is connected correctly. Mine once came loose and I started bucking hard under full boost. Felt like fuel cut or probably was but went away once I got the TPS connected correctly.