Street port Idle quality information
 

I just installed my engine and am running it with any boost for now. I have noticed the idle quality is not real good, it does smooth out above 3k fine and I have not driven it as yet. I adjusted my throttle sensor but I am not sure it was done correctly. I don't believe I have any vacuum leaks as I have checked this for hours. My 02 sensor reading at idle is around .6 and not varying at all as I have seen in the General motors cars I work on. Normally you see a sweep from .2 to .8 or so. The fuel pressure is 38 at idle and snaps to 45 when I give it some throttle. It does run rough at idle and am asking for some input. Thanks in advance.

Street ports normally have a rough/lumpy idle. Typically, the larger the porting, the rougher the idle.

Thanks for the information, I have not taken a compression test but the engine has only run for about an hour or two. It seems like a old V8 with a big camshaft.

Does it sounds anything like this:

http://flathat.woodstream.net/Columb...et_Port_IV.WMV

?

It does sound a bit like that, with out the black smoke. Can you elaborate a bit more on the subject?

That's basically what a street port sounds like (give or take the size of the porting).

That was NoCab's car with a Pineapple ported engine. I believe that was the first start of the new engine install.

Also keep in mind nocab has a single turbo, midpipe and what looks like an apexi GT-spec exhaust. That is about the loudest combination I can imagine.

wow, that is music to my ears! love it.

I have a mild streetport and I am still breaking in my engine. Th idle was lumpy at the beginning but seems to be settling down.
I guess your port is more extensive than mine.

no it's not, the map sensor wasn't plugged up

that's what a half bridge sounds like (almost)

a street port will be lumpy, but it sounds like yours is an incorrectly adjusted throttle body assembly (whether it be the TPS or something else)

if it's enough to cause a concern for him to post, it's probably not just the port

I don't know if Nocabs was plugged in or not....but I do know that there are streetports that do sound like. I know because I've owned a street ported engine that had that much lump to it. CJ

i have a mild street port and my car does brew coffee and make popcorn at idle especially when it hasnt warmed up yet.

Exactly. While that was not the best example to use (as yes, NoCab's MAP sensor was unplugged as he reported), it does give a good indication of what a ported motor will sound like.

I've heard quite a few different ported motors in person(from Pettit and Pineapple in particular), and they are all lumpy/loopy at idle.

If someone has never heard a ported engine idle, then going from stock ports will most likely think something is wrong with the car.

I have a mild streetport from KDR, and the idle is very smooth. Its not a very aggressive port that dave does, and thats fine w/ me.

Nice video! I'm looking into a mild street port myself. Hopefully I'll keep a good idle...

Streetports DO NOT have a lumpy idle. They hiss/crackle more but that's it. I have mulitple streetport templates, they all idle's perfect, even my large one. Bridges,half bridges, etc idle lumpy...

I guess that depends on your idea of "lumpy". Street ports (aside from mild ports) definitely do not idle like stock ported engines.

I have a stage 2 street port from Gotham Racing that has SLIGHT overlap (I've been told). While the idle (when warm) "lopes", I don't have any problems with the car stalling. Basically the idle bounces from 950 to 1000, cyclically.

I can best describe it as a cammed out V8. Starts everytime first crank and works fine warm or cold. I actually love the sound of it. When the car is cold, the idle is too high to notice the "port".

I have had other posts that indicate a warm idle problem (specifically @ 88 degrees on the commander), but this is unrelated to the porting of the engine.

If a streetport has a lumpy idle then you need to tune the idle. Streetports idle like stock. I have a streetport template that has made in excess of 700 rwhp and idles glass smooth at 950/1000 rpm.

i never heard a streetport that sounds like that

mine sounded like a V8 with a cam after i did a street port.

You should be able to get it to idle correct but will sound different. Adjusting the settings and waiting a bit for you compression to settle should help.

My pettit streetport with programable microtech ECU idles smooth as silk. Whow, do I sound like a nascar guy that just won a race

most of you guys that have smooth streetports do not have agressively ported exhausts....

so you've increased the duration of the intake, but you haven't made the exhaust close later or the intake open earlier...

and putting my half bridge next to FD_Newb_1974's car is a big difference....but if i had never heard my car, i'd say his car lopes and idles rough...so you're right Mahjik, i guess it's all about perspective

You can't hear my car idling over yours...when yours is 40 feet away too!

Amazing how the different port jobs and exhaust setups make a car sound.

ported by the same person :D

I'm driving one of Mr. RX7 TT's streetports, and frankly, I cannot tell the difference in idle quality from stock ports. We also installed the PFC at the same time the streetport was done, and that made a world of difference in the idle quality, too. It maintains a nice smooth 800 rpm idle, and pulls seamlessly through the rev band.

I have been building roataries for over 20 years. I have ported every port imaginable. I know EXACTLY what an "aggressive" streetport is. If tuned correctly an aggressive streetport will idle smooth...

I agree with that statement completely.
I made my ports fairly large for a street port and my idle sits comfortably at 700-750 rpm at Idle. No lope.. Only get it slighty at start up. If its lumpy you have too much fuel going in. I'm doing that with a purple box too if you can belive that.

Mr. RX7TT.
You the fellow who came with Rob and drove the black Fd at MIR, Import Vs. Domestic last season?
That was my first day on the track.

i was referring to the exhaust....

if you get agressive with the exhaust, it will NOT idle smooth

Uh, yes it will. I have ports that you could put a tennis ball in...glass smooth idle. Where are you getting this idea from?

this thread should prove interesting.......

I wouldnt say my exhaust ports are all that large..
The are however much larger than stock and still I also have a smooth idle.

Guys, in J.S.J's case his car is all stock aside from the streetported engine he just dropped in (so he's using the stock ECU unless he just ordered a PFC).

While I'm sure you can adjust ECU's for a better idle (as the streetports I've heard on PFC's are smoother than those on rechipped ECU's), that's not the case for the starter of this thread.

if hes using a rechipped ecu or no ecu at all then he should have a bit of a rough idle
reason being the ecu sees less vacuum through the map sensor and will try to adjust for more fuel because it thinks that youre accelerating ,thats why most of rechipped or no ecu whit streetports have wierd idle and rich idle

not the size of the exhaust port, but rather, more importantly, the opening/closing characteristics

I understand the system is running real rich at idle and I am lucky to have 15 inches of vacuum there. I did attach a vacuum pump to the map sensor and the idle did smooth out a lot. I also leaned the mixture by pinching off the fuel fuel line and it ran smoother for a second or to. As I understand using a system interface to tailor the A/F ratios is needed. I just put 15 gallons of fuel in the tank and it is going fast. With an engine which is street ported and maybe a down pipe what P.F.C is the best overall for someone who wont likely mod further than this?? You guys know the best stuff to use and I don't want to run the engine a lit more running so rich.

Might want to verify that the coolant sensor and the fuel temp sensor were in the right place since they're the same color and same fitment. I have seen alot of people messed this up when they drop an engine in their car.

THANK GOD , i thought i was the only idiot who did that mistake ,that sucka got me good one time

I have a lumpy/ loopy idle and I'm in the process of tuning my microtech. Are you saying that Its possible that a good idle tune will drop me from 1200rpm-1000rpm to 800rpm with smooth idle and less gas consumption? this is my dream hahaha please explain. I thought it was impossible for street ports to idle smooth and low. Now I'm thinking it's my idle that's fouling my plugs...