Bucking

[Young Gun]

Just finished a 88 shelby z with an 89 T1 2.5 block and the rest T2(including SMEC). Just put in a T2 clutch with T3 pressure plate.

Drove it for about 140 miles with no problems at all. Then while driving it started to "buck" in forth while building boost. So went to fifth and just cruised and it was fine unless i attempted accelerating and vacuum started to drop. Got it home and just went around the block and the bucking happens anytime the vacuum starts to drop and head towards boost.

So I had to swap in my other cluster to pull codes. I got a 22. Went and got a new CTS. Installed it. Checked codes and it was still there. Drove it and still bucked, still has the code. Decided to check the wires for the CTS. Everything seemed good but I took it all the way to the SMEC. While there I changed out my 2.2 for a 89 T1 2.5 and i attempted to push in the wire further into the connector. Put it all together. Check codes and it is gone. I get all excited and it ended up still bucking :bang head. Checked for codes and there is no codes. I'm at a loss as what to check/try now. Suggestions?

[cordes]

Are you controlling the 2.5 with a 2.2 computer? That's not a good idea for a host of reasons if that's the case. Are you running stock injectors? How are you controlling boost?

[Young Gun]

Are you controlling the 2.5 with a 2.2 computer? That's not a good idea for a host of reasons if that's the case. Are you running stock injectors? How are you controlling boost?

Yes I was temporarily using a 2.2 but the 2.5 computer is in now. Never touched 3,000 rpm's anyways, got to break in the new clutch. Running stock injectors for now planning on upgrading to +20's shortly. Controlling boost the factory way for now.

Just makes me mad that it was running great and now its un-driveable again!

[turbovanman²]

Check fuel pressure, plug wires, plugs and ignition coil.

[Young Gun]

Check fuel pressure, plug wires, plugs and ignition coil.

oops forgot to mention fuel pressure was at 48psi at idle...didn't think it would cause such bucking?

fuel pressure regulator was fine at 55psi when i unhooked the vacuum hosing from it

Plugs/wires/cap are all new

[cordes]

oops forgot to mention fuel pressure was at 48psi at idle...didn't think it would cause such bucking?

fuel pressure regulator was fine at 55psi when i unhooked the vacuum hosing from it

Plugs/wires/cap are all new

FP should drop when vac is applied to it. I would think that it should actually be slightly lower if your timing is spot on, but it could be a gauge issue too. How much vac are you pulling at idle?

[Young Gun]

It is all better now... pulled the plugs and #1 was all gummed up and gapped incorrectly. I was in a rush when installing and only visually inspected one plug out of the box, Never again will I make that mistake.

She is all happy now with another 150 miles under her belt

[cordes]

Glad to hear that you have the problem solved. Also, have you checked out the local SDAC club in your area? IIRC there are several long time members in your general area.

[Young Gun]

Not yet. Another member reached out to me and helped me with the swap being it was my first major automotive work

[Young Gun]

Doing it again -___-. #1 was horrible, #2 was dirty and 3 & 4 were turning brown. Little smoke on start up then its done. Cleaning the plugs up along with the intake hosing as there is some oil in there. Noticed the previous owner installed(or had installed) the muffler backwards and makes a nice puttering sound at idle so I gotta get that flipped too.

400 miles on it now..

[RoadWarrior222]

There's a "mechanical" sound from the muffler? If it's a baffle type, it's possible it's damaged from reverse install and has a plate broke loose that is "valving" and screwing things up.