B18C Build Troubleshooting

I’m rolling to showtime’s place later saturday afternoon, i could roll by earlier to check it out if you’ll be there…

I’ll be there all morning/afternoon Saturday. I have to run over to drop off a clutch alignment tool, so I’ll pick up a battery tonight.

just wondering did you adjust the plates all the way closed?like take the set screw completely out hopefully?throttle cable to tight?

how did you mount them injectors?used stock part of the manifold?maybe you have a vacuum leak through teh injectors?

do you have one of tehm vacuum chamber thingies?make sure eveyrthing is caped?

you need air to rev higher, find out where its coming in from :slight_smile:

Well:

New battery, double checked the plate closing issue. Car starts fine, idles smoothly at 3K…and covering the tops of the velocity stacks kills it instantly. :wtf: I don’t see evidence of vacuum leak, so I’m no closer to figuring it out.

I’m starting to think

  1. slop in the butterflies
  2. the idle drill-hole you may have drilled is too large

Is there any holes in the face of the butterflies? Do the butterflies have any more adjustment? Are they flat or were they bent before? Are the bending past their stops and causing air to come in on their “other side” rotating into the negative throttle zone? Do you have air filters on the horns yet?

I didn’t notice any slop in the butterflies, I checked them as closely as I could. As for the idle drill hole, there is one in the bottom of each runner…not on the plate itself though. They are pretty tiny, I’d say no larger than 1/16".

I do have filter for each runner, but they are not on as of right now…when I ran it before the build I did have them on with indifferent results.

you drilled a hole?

I dont know…i give up…I will try and stop over this week and help figure out your issue.

No I didn’t drill anything, in fact I left the vac ports you installed in the Suzuki injector ports (only because the pitch of the port is too extreme and would fire fuel into the floor of the runner so atomization would be teh suck).

There are tiny holes in the floor of each throttle body, that appear to bypass the plate, but there is nothing that could possiblly control them…unless the secondary butterflies on the GSX-R are what modulate the flow that seeps past the primaries:squint:

so there are 4 tiny holes after the plates??? that would be the first place i’d start! :tounge:

I’m not sure off the top of my head if the do indeed surface after the plate or not.

On the bottom side of each throttle body, there are two small nipples. All of these have been capped off, I was under the impression that the tiny holes on the inside ran to them…if they don’t then why would there be two blind nipples?

well whatever the case may be, there should be nothing open between the plates and the head… even little 1/16" holes

i hope you get this thing running soon steve , im excited to see it…

:weak:

no shit.

Well, last night generated a whole host of issues. I readjusted the plate for the fiftieth time, they are 100% closed now…nothing I can do about he bypass holes.

This time I began datalogging before I even turned the key:

Idled at 2500, then slowly crept up to about 3900 before the CEL came on solid. I checked the codes and TPS, MAP, CKP, O2 came up…these NEVER appeared before except for TPS since the wire fell out.

Looking at the datalog was alarming. With NO throttle input the TPS signal voltage is all over the place, not steady at all. Ranges from .0V (where is should be) to 1.0V. MAP sensor is seeing no less than 650mBar which is near the bottom right hand corner of the low cam fuel map (way too high for idle). MAP pressure actually starts high and as RPM rises the pressure displayed goes down. Actual timing is showing in the range if +45…again too high.

I have a feeling the TPS is useless, and the current MAP configuration is not optimal…throwing everything out of wack.

I may pull it all off tonight and put the stock manifold/TB back on. At this point…given all the ground I have covered…I just want the thing to be drivable. I already missed two event, and don’t want to miss more fucking around.

What a mess…

you sure you dont have some sort of ground problem? Unless you have a problem with every one of those systems, i’d guess grounds. but who knows.

…and people yell at me for building honda itb’s, yet you plug them in and go :nuts:

Grounds are all brand new, 0 or 2 gauge for all points…sanded contacts with copper terminals.

What do you mean plug and go? IF you are inferring I did that…you’d be way off. There has been months of plannng to get it where it is now. What could possible cause an epic fuck up like this is beyond me. I have never seen values like that, especially on idle/start-up.

Well its good that you’ve grounded it well.

I’m not saying that you didnt do it right, its just that i’ve built ITB’s out of honda RR’s with great sucess. The tps and map plug in and your done. no calibrating, no mysteries… plus the 954rr’s are 42mm at the plate as well.

previously, you said there was nothing you could do about the bypass holes… you are refering to the pin holes on the bottom of the runners that are left open? They need to be sealed. Any air getting in b/w the plates and the head is going to alow it to run irraticly, change map figures, etc. Also, when you got the plates 100% closed, did you try again to cover them with your hand to verify? It should not have shut off at that point IF the plates were closed.

This is a dumb question, but can the bypass holes be taped off temporarily? Just to see if it makes a difference? I was going to vote grounds also but I remember seeing under Steve’s hood awhile ago and it was pretty well done.

Well, first off you used a Honda TPS with CBR ITB’s…I’m using a Suzuki so it must be calibrated no matter what. Secondly the signal voltage is NOT STABLE like it would be with the stock (or a good) TPS, indicating that it is probably shot. That alone will throw things way off. I have read many times that the CBR TPS is plug and play, and that you supposedly cannot use the Suzuki one…although that assumption was made when someone threw it on and did not adjust/calibrate the TPS.

You may be right about the MAP sensor, but I have no idea how you mounted yours…both in relation to the throttles and to the vac system as a whole. Mine may be seeing too much vacuum.