Hi guys,

I've got two concerns I'm hoping someone can help me address... I'm no genious in this field – it’s just a hobby, so any input would be appreciated

My setup :

V2 supercharger, 3.33” pulley, A/F gauge (REALLY wish I had gotten an EGT which will go in ASAP), 6:1 FMU disc, NGK BKR6E copper plugs gapped at 0.039.

The two problems :

- The plugs have about 10k miles on them, and they are in as good as new condition : I should be seeing more deposits on them I think... I'm worried that I'm running lean/overheating them... or do our cars never foul plugs and am I worrying about nothing?

- Car runs unevenly on a cold start; only when around 1100-1300rpm though and only when it's colder out.. if keep around those rpms in gear the car surges - sort of like in limp-home mode. Once the engine warms, that goes away.

The plugs are what I’m worried about most. I’ve entertained a few possibilities; I realize some may be far-fetched, but I’m trying to come up with anything to make me feel better. The first thing that crossed my mind is that the mixture is leaned out most of the time anyways, except for when running boost or when at WOT. My discount A/F ratio gauge usually shows me running lean.. do I just need to give them more time before worrying? How do your plugs look under “proper” conditions at around 9-10k?

A few other things that came to mind.. colder air = greater air density, and I am always running 94 octane... both factors can cause more heat (gotta love that 10% ethanol content in Sunoco 94 – I heard it also makes a great agent in cleaning deposits). Maybe I’m not running lean after all?

I’m hitting myself for not getting an EGT gauge, but I have to settle for the A/F ratio for now.. which still tells me I’m running rich - but from what I've read that's more believeable than a lean condiition with my setup. Still.. I don't want to destroy my motor just yet... I’ll have to get the EGT if I want to start toying with the S-AFC down the road..

With regards to the cold-start problem; I’ve scoured for vacuum leaks and found a small rip which has been fixed by a replaced line.. but that only did me psychological good Maybe colder NGK plugs hate Canadian climates? Perhaps I should lend my car to someone who lives in a warmer area until things shape up around here...

 

how many miles on the car?

Any tune ups forseeable? (like a 30, 60K'er?)

 

About 55k miles (I'm in kilometers ). Not sure about the maintenance book, but all my fluids are fine, and the fuel pump won't be coughing up any hairballs anytime soon

 

This is just an idea, but it worked on another car of mine.

Check/change the PCV valve. I had a camry before, and the valve was getting old (via 60K miles) and I replaced it. She suprisinly smoothened up.

Just a suggestion, don't know if it will cure anything.

 

The idea came to me but I didn't look at it.. heck here's something to do next weekend!

 

I'm getting about 11psi of vacuum at idle.. Does that sound right or do I have a leak somewhere?

 

I'm getting about 11psi of vacuum at idle.. Does that sound right or do I have a leak somewhere?

 

hmmmm... How do u know when there is a leak??

 

I read somewhere that is low. Possible leak



Jer, BenBlanco was running lean, and he used some fuel injector cleaner at fillup. He says that he has not had a CEL all week so far. PM him. Great guy and willing to help you out. Sorry I can't help more.

-fnny

 

Isnt 18 about normal?

SuDZ

 

I thought 19-21 was normal.. Hmmm. I gotta check my wires over the weekend..May sure all my t-taps are nice and snug.. Any suggestions on what I should be checking first?

 

Try the T Tap for the boost gauge. BOV, and actual plumbing while your at it

 

And if all else fails, try another boost gauge!

Thanks for the injector advice... maybe I will go for an injector flush... I've got quite a few km's on the car so it can't hurt - before I installed the s/c I usually filled on Esso which has the highest lead/crap content around here I sorta figured the ethanol content in the 94 octane that I fill up on would clean them out.. feh we shall see!

 

Say, Jer...what brand and style of gauges do you have?

 

What's the most accurate Boost gauge to get out there?

 

11 psi is good vacuum. Normal vacuum at idle is 18-22 inches of Hg, which converts to ~9-11 psi. Now, are you sure your vacuum gauge is calibrated in psi and not inches of Hg?

 

11 psi is good vacuum. Normal vacuum at idle is 18-22 inches of Hg, which converts to ~9-11 psi. Now, are you sure your vacuum gauge is calibrated in psi and not inches of Hg?

 

I'm positive.. It's the cobalt series boost gauge.. It's in PSI.. So then what I'm getting is normal?

 

11 psi is quite normal, even better than what most people are getting.

 

Autometer Phantoms; I got the Boost, A/F and Trannie Temp... picking up the EGT and Fuel pressure; I doubt I can fit 5 gauges so the A/F will hafta go

Stephen : 11psi is normal? How come we usually see 20 on idle!?

PCGuru : Cobalt gauges are sweet looking! When I was ordering my S/C they had just made the initial run and then delayed the next batch for 1.5-2 months I wanted them soooo badly

 

Yes, 11 psi is normal. So is 20 inches of Hg. 20 psi of vacuum is not possible.

 

Hmm, oops I am a moron.

Forgot that everything before the zero is not measured in psi but rather Hg/something-something

 

You're right it is inches of Hg, not inches of H20 like I stated (I edited my posts). Basically, atmospheric pressure (14.7 psi) is able to support a column of mercury roughly 29.9 inches high. Somewhere in dim ages past, vacuum came to be measured in inches (millimeters) of Hg, even though positive pressure is measured in psi (or Pascals). The result today is boost gauges with two scales depending on if the pressure is + or -.

 

So then I should be showing 20 HG?

 

Yes, but didn't you say your gauge is in psi? If so, then 11 psi is a good vacuum at idle. 11 inches Hg is waaaay low, indicative of a vacuum leak. Do you have a link to a picture of your gauge?

 

It's the Autometer Cobalt. Right under where it says Vacuum I see "in HG". And then for boost I see PSI.

 

Okay, now we're getting somewhere. You are getting 11" Hg of vaccum at idle. That's too low, 18-22" Hg is normal. You've got a vacuum leak.

 

Yeah I figured that.... It's too freakin cold though to go outside and check

 

When you guys say "At idle", so you mean in gear or Park/Nuetral.

I'm 15 in P, 12 in D. (Hg)

I've removed my manifold and re-sealed it with new gaskets several times (and RTV) - replaced every hose in the vacuum system, done a compressions test (which looked great), and tried 4 different gauges - all with the same results.

I gave up about 6 months ago.

 

PcGuRu, i just noticed in ur sig that you ran the 1/4 in 14.9?!?! and ur SCed with 297 FWHP? I was seriously considering supercharging my i30 but i was expecting to see a little bit better results... didnt kev run it in 12.8@112 or some crazy number when he was auto?

 

When I was ran my 14.5 I was only at 245fwhp cuz I was running super rich.. I loss about 55hp that I gained from the afc.. With that gain I'm sure I'll see low 14's possibly high 13's...

 

At idle means in neutral or park. If you're in drive, then you can expect slightly lower vacuum because the idle speed goes down a bit due to torque convertor drag.