Hey all,

so yesterday I finally got arround to installing my Crawford upper plenum. It was missing the male coolant hose spouts that's go arroud the throttle body, so I ended up buying a motordyne copper themal spacer becase it comes with them attached. After installing the crawford plenum and TB spacer, I plugged everythih back in, re connected the battery, reset my ecu and tried firing her up. Upon starting the car my engine began chugging very hard and idling at very low rps. Almost stalling several times. The RPM would raise to 1500, dip to 200, and continue to chug very inconsistantlly at idle.

I don't think there is a leak in the plenum because I even purchased a new gasket from the stealership for 40 dahllah. All hoses are connected and the TB is bolted down tightlly.

Is it possible my engine is running too Ritch / lean? I have test pipes, full Catback true dual hks exhaust, z tube and stillen intake, Crawford upper plenum, and copper tb spacer. This pretty much is everything on terms of respritory mods (except for headers and mrev (nonrevup) ). So would I expect my air flow to be all out of whack after those mods If I havnt tuned the car yet? Would a tune correct my choppy idle and smooth out my a/f ratio? Or should my car be running fine regardless of a tune?

Any input on what could be causig this very aggressive unstable idling would be appreciated. I can upload a video with sound this afternoon if that helps.


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Did you mess with the maf sensor? If you messed with the throttle body then you might have to have it reset. Atleast the idle air volume learning procedure. Check the motordyne website. I think the throttle body reset instructions are on there. If its not this then it sounds like a leak.

 

^ no, he has the MD TB copper spacer. It sounds like you have a vacuum leak or the MAF isn't pluged in correctly.

 

No lol. Although I was considerig it hahaha. But the fittment would be off and that would be waaaay too much volume. I originally had the 5/16 spacer. Took that off and added the Crawford plenum with no spacer (new gasket between both pieces). I purchased just the copper throttle body spacer only from another member so I would have the coolant ports behind the TB.

 

^^ sorry. I misread your post, and edited my statement. I think it needs a throttle body reset.

found this also:
http://www.350zmotoring.com/forums/3...-stalling.html

 

I'm fairly confident the plenum is bolted down tightly. Where
else could I have a vaccume leak? All hoses and maf are secure. Would I be able to hear a leak if there is one? My engine is chugging very hard (although still driveable). How much of a leak would be enough to cause this? Little to any, or would it have to be a major gap? Could my tb not be positioned correct? I'm noticing lag time between pressing the accelerator pedal and Rpms raising. I'll ease on the gas and it will wait a
second them suddenly jolt up.

 

Great find! I'll try all of their suggestions. Sounds like he has the same problem as me.

 

After you fix your problem, I would defintiely recommend a tune. Unless you plan on getting headers....

 

ok I tried resetting the ecu, resetting the brake / accel pedal position, resetting the throttle body position, resetting the idle air flow setting, and the problem still continues.

It sounds like there is a leak, but I re torqued all the bolts and made sure its air tight, I also checked all the hoses and they are firmlly connected.

I have a new gasket that i put arround the lower plenum and checked the TB gasket as well.

MAS is plugged in and so is the TB electric clip.


STILL chugging and very rough idle. one of the screws is missing but I know it isnt the cause of the problem.

I made a video to show everyone. (you can see the missing screw but I explain in the video that it isnt the source of the leak)

hopefully the video helps to show the setup and maybe someone can give a solution.


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bump

 

It looks like you didn't replace the two guide pins on each side of the plenum. Might want to take those out (I think you can use 4mm socket) and replace with some m6 bolts. Check the lines for cracks as well. I had to replace one of mine not to long ago due to it cracking.

I'm off work tomorrow Jeff and can take a look in the morning or if you want to swing by tonight too.

 

Thanks for the tips chris. I'll look at those pins and check for cracks when I get home. If I still can't fix it I'll give u a call.

 

Sounds good Jeff

 

i had a similar issue when my MAF connector wasn't fully seated. other than that, i'd throw some M6 nuts on the two pins on the sides of the manifold and find a screw for the top of the plenum. if its still struggling, spray a little carb or throttle body cleaner around the plenum, hose connections, and vacuum lines - the idle will smooth out when you find the leak. this doesn't always work, but you may get lucky

 

I'm still not sure why you replaced your 5/16" with the crawford? I have the same crawford V5 and haven't experienced the problems you are having. But I never disconnected the battery and I kept the TB plugged in.