engine power seems lacking at midrange

[stlrj]

Originally Posted by bickyd

I really appreciate your words of caution. But I am beyond recovering from this addiction I am afraid. Cheers.

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That's just what I wanted to hear, now let the fun begin!

"I would like the parameters of the injectors to be as close as possible."

That's what I was looking for too initially but found that these new style highly efficient atomizing injectors do not need to flow the same as the old pintle style Bosch injectors and yet produce more power and torque more efficiently. To my surprise I found that lower flowing EV6 or Multec injectors performed much better than injectors of the same flow rate as the stock Carrera injectors.


Another hopelessly addicted soul,
Joe

[bickyd]

I noticed that the 17109448 injector is rated for 180 cc per minute while the stock single Pintle injector flows 229.1 cc's as per Weiss. Injector rehab site says 296 cc's per minute for the 0280150158 stock porsche injectors. So conflicting data. I am inclined to go with Weiss. What you say makes sense because of atomizing efficiency. More bang. And resulting efficiencies across the board. More cooling affect. Improved mileage and drive response. You have done the wheelbarrow work for me. Now have a beer. A Westmalle trappist on me.

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[stlrj]

I also noticed that Porsche downsized the four hole EV1 Bosch injectors on the 996 when compared to our 3.2 Carrera injectors. It seems since the 996 displacement is larger and putting out almost 100hp over our Carreras that the flow rates would be much higher. Yet the 996 injectors flow at 220 cc's while our 3.2 Carreras flow at 229 cc's. Considering the differences in displacement and hp you would think the 996 would have injectors flowing closer to 250 cc's. Hmmm.

[bickyd]

Good point. An interesting Avenue for thought. It's seem with that analysis between our Carreras and the 993. We have some power left on the table. I would assume fuel pressure is adequate to provide volume but the efficiency of our volume is suspect. Your pick of the 9448's seems to be an a hint of proof in this by your reports of improved performance. They are reasonably priced on ebay too. Onwards...

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[E Sully]

Getting the car to run well stock should be done before playing with chips and injectors.
When was the last time it had a tune up? Plugs, wires, distributor cap and rotor. How does the inside of the distributor look? Do the weights move freely. The 3.2 timing is controlled by the DME, but the distributor centrifugal weights keep the rotor in phase with the contacts. The felt should be lightly oiled on occasion.
You can also make sure the idle switch and full throttle switch are set right and working.
Are there any air leaks? Make sure the intake runner allen bolts are snug, and check to see if any vacuum lines are loose or cracked, along with the lines to the cruise control. I had a leak at the fitting circled in this photo.


Another area to check is the AFM wipers. Some high mileage cars have the contact strip worn out, and re-positioning the contacts can make a big difference. The links in this thread seem to be dead now, but it should give you help in checking it out.
FR Wilke's AFM mod a success (and easy)

[Trakrat]

Originally Posted by E Sully

Getting the car to run well stock should be done before playing with chips and injectors.
When was the last time it had a tune up? Plugs, wires, distributor cap and rotor. How does the inside of the distributor look? Do the weights move freely. The 3.2 timing is controlled by the DME, but the distributor centrifugal weights keep the rotor in phase with the contacts. The felt should be lightly oiled on occasion.
You can also make sure the idle switch and full throttle switch are set right and working.
Are there any air leaks? Make sure the intake runner allen bolts are snug, and check to see if any vacuum lines are loose or cracked, along with the lines to the cruise control. I had a leak at the fitting circled in this photo.


Another area to check is the AFM wipers. Some high mileage cars have the contact strip worn out, and re-positioning the contacts can make a big difference. The links in this thread seem to be dead now, but it should give you help in checking it out.
FR Wilke's AFM mod a success (and easy)

Good info... I'm planning on replacing all plugs and wires with a slightly better performance options. From what I've been told, vacuum leaks would affect idling, and my car idles absolutely perfectly?? I'll have to check the distributor.... it seems difficult to open up and didn't want to mess with it yet.
Nonetheless, I already have a set of new headers and exhaust on order as well as a new chip replacement to support the exhaust mods... but I know that this will only mask the problem and want to find the issue in case this leads to something more serious.
On a side note... could this be a symptom of a cylinder leak? I haven't had one, but I guess it wouldn't hurt to check the compression.

[stlrj]

Originally Posted by bickyd

I noticed that the 17109448 injector is rated for 180 cc per minute ...

I obviously need to update my reference material since I was unable to find this flow rate on the Weiss site. Which site has this information?

Cheers,

Joe

[bickyd]

Witchhunter. Com/flowdatapix/rp17109448.jpg states flow at 178 cc's .

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[bickyd]

Www.injectorrx.com/rochester-fuel-injectors/ I just realized you are an engineer. I will now talk less and listen more. I hope this helps.

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[stlrj]

Originally Posted by bickyd

Witchhunter. Com/flowdatapix/rp17109448.jpg states flow at 178 cc's .

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Wow, I must be getting old. I have that site but didn't see it 'til you told me.


Joe

[stlrj]

Originally Posted by bickyd

Www.injectorrx.com/rochester-fuel-injectors/ I just realized you are an engineer. I will now talk less and listen more. I hope this helps.

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Correction: Stationary Engineer