I put an engine into a second gen n/a 6 port recently. It's having a weird problem though. Below 3k it has a hesitation and a studder, above 3k it seems to rev all the way up, but it seems to be lacking on power. The engine is just past the break in point, and I have the timing set right in. I switched out the coils/plug wires with ones off a turbo 2 at my garage and the problem got a little better, but it is still there. What else could be causing this? The n/a can run on normal 87 octane even though it's ported, right?

BTW it has a few mods, but I don't think that would cause anything
downpipe
midpipe
catback
intake
ported engine
no p/s
no a/c
no OMP (running premix 100:1)

When I put the engine in, I replaced:
o2 sensor
spark plugs
fuel filter
and all the usual fluids

Thanks for your help,
Jesse

 

sounds like a sticky injector (hesitation) and 5th & 6th port activation problem (lack of power up high)

edit: but where does the lack of power start about 5,500-6,000rpm?
and what kind of hesitation is it? a dead spot in the RPM band under 3,000 when you go WOT, or just a rough acceleration?

 

kind of a rough acceleration when not at WOT under 3k The lack of power is kind of all the way up though... starting when I go WOT.

 

I would say get your injectors cleaned professionalyl or replaced and have a look and you solenoids on the aux. ports and the ports/actuation rods themselves while the injectors are being done

 

to test the aux ports...if I give the actuators a vacume source... they should open the ports, right?

 

yes...migh want to start by disconnecting the solenoids and try to turn the actual rod itself - 9 times out of 10 they are siezed solid

 

they should be able to be moved by hand then?

 

yup

 

can someone tell me what WOT is ... sorry for the tard question.

thanks

 

WOT=Wide Open Throttle

You didn't mention what year, so this may or may not be relevant, but- When I got my S5 2nd gen, it ran close to what you mentioned. I found that the 5&6 ports were wired open, and the air pump had been removed. This means the VDI was always closed. Once I put the air pump back on, and got the 5&6 ports and VDI working correctly it ran a lot better at lower RPMs, and had more power throughout the rev range.

 

do you have new plug wires?

 

It's an s5, so yea the vdi is controlled by the air pump, which is still there. It has new plug wires also. We are going to give new injectors a shot, because it probably needs them anyways. I will test out the aux ports when I have the mani off for the injectors. Thanks for all your help!

 

sounds like it could be ignition to me - how's your spark? did you disconnect the initial set coupler after setting timing? (is that what it's called?) ~rich

 

The spark is good... I tried another set of ignition coils from a turbo 2 at the shop and it didn't change anything. I tried my timing light on all the wires and they are all getting a spark. Also changed the plugs/wires out with some new ones laying around.

ok.... I tried some more things today with this car.....
Replaced all the injectors
Replaced the TPS
Checked the 6ports (they're free enough to turn and the actuators work)

I put it all back together and it still has the problem... I played with the timing some more just to see what would happen.. I put it way out of time and it is almost perfect... wtf? The problem is kind of opposite now... when I floor it, it stumbles, but normal driving is fine. I noticed that the VDI system (double throttles) are taken out of the throttle body, but the 6 port system is still there. Is there any way I could have put the crank pulley on wrong where the timing mark is in the wrong place? I guess I will check it on one of the engines in the shop tomorrow. If I remember correctly, the pulley could only go on one way, but who knows, maybe I messed that up. Man this thing is driving me crazy, lol.

 

sounds like the devils work to me




sorry just had to say it

 

haha, yea.. I agree