Stumbling on acceleration

[BWeston]

Ok so I bought another dsm yesterday, It was initially running on 3 cylinders due to no cylinder fire in cylinder 3. I changed the plugs, plug wires, coil pack, and power transistor. It's no longer missing, it has a nice idle to it though it surges a bit. It does not accelerate very much at all, at half throttle around 3k rpms and up it starts to break up like it's not getting fuel. So i changed the fuel rail that had a different stock 2g fuel pressure regulator, all 4 injectors, and I changed the fuel filter. It's still breaking up the same way it was before until it's not even hardly hitting at all. So I've changed all the ignition system components, and all the fuel components except for the fuel pump itself. I need you guys to throw in your 2 cents. I can't help but think it's the fuel pump.

 

[Black'95]

Ignore the P port. Unless someone effed with it - that's how it comes from the factory.

Is it different on a 98, then? Both my 95s had a line on all of the ports on the throttle body..... I believe the 'P' port goes to the evap purge valve and solenoid? Also, I just double-checked, and RRE says some people connect their boost gauges to the P fitting, but there is no vacuum present there, only boost pressure. Here's the link:

RRE VDO Boost Gauge Installation Instructions

I can't imagine the factory would leave that fitting open....

 

[1MeanTSI]

check to see if your fuel lines are clogged as well, clogged injectors would be my first guess but, you changed all that I would say check ## fuel lines then, run a blt!

 

[FUZZYDESERTDSM]

do a gap check on the plug, ngk plugs are a big plus if you don't have them on your car already, plus one on everyone that said boost leak and major plus one on the soap and water method. good luck

 

[zanderson]

Is it different on a 98, then? Both my 95s had a line on all of the ports on the throttle body..... I believe the 'P' port goes to the evap purge valve and solenoid? Also, I just double-checked, and RRE says some people connect their boost gauges to the P fitting, but there is no vacuum present there, only boost pressure. Here's the link:

RRE VDO Boost Gauge Installation Instructions

I can't imagine the factory would leave that fitting open....

If there is a nipple on the TB it needs to go somewhere or be pluged, it will cause a boost/vacuume leak. Probably not significant, but a few here and there and it becomes a big problem.

Presurizing the whole system through the inlet of your turbo with an air compressor is going to be the best way to find leaks, and the quickest. Get a spray bottle with some soapy water and hit your intercooler pipes all over not just the connection points they may have cracked. Also make sure to get around the throttle body. I'd bet you'll find the soapy water bubbling around that nipple.

If you are running NGK plugs, and they are new your just fine gapping them is worth your time, but I ran ungapped plugs for the longest time and didn't have any cutting out or bogging down just probably didn't see the power that I should have.

I did'nt see, are you running the stock turbo, MBC? you could be hitting fuel cut. Also have you put on aftermarket exhaust, too big of an exhaust can be know to cause boost creep with that and if you are running a more boost than stock your could be having fuel problems. Sorry if I over looked your mods.

 

[BWeston]

If there is a nipple on the TB it needs to go somewhere or be pluged, it will cause a boost/vacuume leak. Probably not significant, but a few here and there and it becomes a big problem.

Presurizing the whole system through the inlet of your turbo with an air compressor is going to be the best way to find leaks, and the quickest. Get a spray bottle with some soapy water and hit your intercooler pipes all over not just the connection points they may have cracked. Also make sure to get around the throttle body. I'd bet you'll find the soapy water bubbling around that nipple.

If you are running NGK plugs, and they are new your just fine gapping them is worth your time, but I ran ungapped plugs for the longest time and didn't have any cutting out or bogging down just probably didn't see the power that I should have.

I did'nt see, are you running the stock turbo, MBC? you could be hitting fuel cut. Also have you put on aftermarket exhaust, too big of an exhaust can be know to cause boost creep with that and if you are running a more boost than stock your could be having fuel problems. Sorry if I over looked your mods.

The car is nearly bone stock, no upgrades except for a K&N fipk I put on it. it has an exhaust leak, but i don't know how bad it is. the plugs are gapped to .028. I'm gonna perform the blt tomorrow, I have to go get everything i need to make one first.

 

[4g63awdtsi]

Boost leak somewhere for sure

 

[my dreamt dsm]

My rule of thumb, do the free stuff first.

 

[PieEyedPiper]

Is it different on a 98, then? Both my 95s had a line on all of the ports on the throttle body..... I believe the 'P' port goes to the evap purge valve and solenoid? Also, I just double-checked, and RRE says some people connect their boost gauges to the P fitting, but there is no vacuum present there, only boost pressure. Here's the link:

RRE VDO Boost Gauge Installation Instructions

I can't imagine the factory would leave that fitting open....

If there is a nipple on the TB it needs to go somewhere or be pluged, it will cause a boost/vacuume leak. Probably not significant, but a few here and there and it becomes a big problem.

Presurizing the whole system through the inlet of your turbo with an air compressor is going to be the best way to find leaks, and the quickest. Get a spray bottle with some soapy water and hit your intercooler pipes all over not just the connection points they may have cracked. Also make sure to get around the throttle body. I'd bet you'll find the soapy water bubbling around that nipple.

There is no nipple. There is no leak.

http://www.dsmtuners.com/forums/newbie-forum/301941-installing-early-2g-throttle-body-late-2g.html

There is a link within that thread that explains further. Actually there's 2 links, but the threads were merged.

 

[Black'95]

There is no nipple. There is no leak.

http://www.dsmtuners.com/forums/newbie-forum/301941-installing-early-2g-throttle-body-late-2g.html

There is a link within that thread that explains further. Actually there's 2 links, but the threads were merged.

Nice! I never knew the 98-99 cars didn't have the P port open.