here's a challenge question

[rick13]

some background:

upon start up, the car starts an behaves perfectly. unfortunately when i boost past 10psi she begins to flutter and loose power. after about 3 minutes everything is back to normal. boost goes to 18psi and hold on! so, as long as i am crusing all systems are "go".

i exit the highway, come to a stop light, and as long as the light turns green, and i proceed under say...1 minute, i still have full power with boost. unfortunately, if i get stuck at a light for more than a minute or two...the symtoms return. i can't boost over 10psi.

so i cruise for another 2-3 minutes and BAM! full power...full boost...

this continues without fail. she's a demon...so long as i avoid sitting and idling. things do seem a bit rich at idle (i only have a color coded gauge to go by) but she leans out nicely at highway speeds (unless i am into boost)...then the gauge shows the air/fuel mixture increase accordingly.

when i switch out the plugs, she immeadiately has full power and full boost capabilities.

so my question is: what is causing my plugs to foul out at idle... and everything be fine after driving and reving her up?

please help,

rick

[kdjones2000]

A list of modifications would be a good place to start

If you are running rich at idle, then either your O2 sensor is wonky or you for some reason are going into "open loop" control mode on the A/F mixture.

[rick13]

Hybrid turbo. Chipped (can't remember which kind). Stainless headers. 3" exhaust. 3/16" shimmed wastegate. manual boost controller. 3 bar fpr. Freshly rebuilt motor.

All mods worked perfectly together before rebuild.

O2 sensor eh...ya know, when I installed that sucker, I remember getting it all twisted up a couple times. I will have a look.

[rick13]

kd,

tell me more about this "open loop" and how it applies to rich idle and the O2 sensor...

rick

[kdjones2000]

Do you have a wideband AFR gauge or narrowband? If it's a wideband, what is your ratio at idle? On the highway cruising? What about your fuel pressure at the rail? Does your chipset allow for fuel adjustments with the FQS?

Open loop is what your car runs on while the O2 sensor is still warming up, so your O2 sensor information is not being used to control the fuel injectors. A predefined amount of gas is used, depending on other factors not related to feedback from the O2 sensor. Usually it is a bit rich.

[rick13]

i don't know, the air/fuel gauge only reads in color. it has 10 bars...red red yellow yellow green green yellow yellow red red. i can tell you that when i am crusing at highway speed it BLINKS on and off through the first 2 reds and one yellow (lean).

at full throttle it goes SOLID (lights stay lit)up through the green. at idle it varies but usually goes SOLID up through green and one yellow...very rich

probably a cheap gauge i know, but thats all i can tell you.

fuel pressure at rail goes to +-43

my first instinct was leaky injector...but i will inspect and test O2 sensor

[nynor]

have you allowed the car to idle for some time and then inspected the plugs to verify that they are fouling?

[rick13]

No. But I will.

[gpr8er]

install NGK BPR7es plugs and gap to .26

[rick13]

gpr8er,

roger that .

i love direct orders

smith out

[nynor]

i think i need to do this in the spring.

[ft_factorytuned]

Hi Rick, I thought I'd through mine in here too! I'd check vac first - easiest.(the entire circuit as it sounds like it's been apart recently..) Reason, (brief) vac transitions from pressure then settles at idle. I have to agree with KD somewhat, with mixture. Usually the Lambda sensor is good, but if it was dropped or truly stressed/really twisted there is a slight chance it's misbehaving. Unless it is simply dying. Not sure how practical it is to swap out the eproms for factory set but that might be a good idea, again not sure if you're using third party engine management or piggy.. You're monitoring the mixture I'm guessing so you can change it at some point??!!

I have seen on more that one occasion this SIMILAR behavior when the ignition driver amp was dying. This would cause similar plug issues as you've been seeing. The amp driver temp swing causes the strangeness. And the general oddness. If you can get your hands on a friends ecu - swap it. Sorry nothing definitive. It is a simple circuit however. Sounds like fuel is good so your left with misbehaving fire, and mixture(air) and their ancillaries..

Good luck and if you really want to figure it out quickly take it to a dyno shop.

FT

[johnkoawood]

SOunds to me like the OP is watching a narow band gauge...

If this is the fact I will throw in my 2C..

NEVER NEVER NEVER watch a NB gauge.. like playing with yourself it accomplishes very little but might make you go blind!

Running rich at idle WILL foul the plugs... next time it is happening, let the car run at idle, shut down the car, pull the plugs and smell them.. if they smell of fuel they are fouled from being overly rich at idle!

I'm willing to bet you ahve a few issues..

1)Verify TPS adjustment
2)Verify AFM functioning properly
3)Verify vacuum line routing

[rick13]

ok so yesterday i pulled my plugs. i had bosch super plus wr7dc. gapped at .026-.027 the tips and arm were slightly brownish/grey, the white resistor part is still pretty white...maybe a little brown/tan and DRY.

however, the bottom of the threads were black/ brown...more black. AND the threads and crush rings were wet! they smell like gas.

just for fun i regapped them to .030-.031 after reinstall it ran like crap. lots of "flutter" and i couldn't even boost past 6 psi!!!!

so i got the ngk BPR7es gapped 'em at .025-.026 it ran much better but i still had same problems...after 5 minutes on highway, 18psi NO PROBLEMS!!!!!!!!!! and of course i come to turn around, sit for a minute and again...boost problems.

JOHN,

i did test check and rebuild (seemed to have a dead spot) my TPS. i did the same thing to my AFM. it also had a dead spot. quite frankly, i am not sure i fixed them properly. i guess i should replace TPS and AFM (because every now and then, i can still feel a bit of a miss around 2-3k rpm)

i am probably going to go with lindsey MAF

yes, no, other suggestions...

rick

[nynor]

i am thinking you have injector problems. were all your plugs wet? pull the vacuum lines at the fuel damper and regulator and smell them.

[kdjones2000]

If the electrode and ceramic are tan and dry, then it sounds like your plugs are not fouled. Pictures are worth a thousand words

You should probably also check the connections to the 2 temperature sensors on the engine. They may need replacing, or could have corroded connections, which can throw off the DME.

Going through all of these things should help to narrow things down, hopefully.

[ft_factorytuned]

Would be nice to know what you found, if you get it figured out before the start swapping in new hardware...

FT

[gpr8er]

my vote is a weak ignition issue. Are the cap, rotor and wires new or in very good condition?

[rick13]

I will check cap and rotor. Wires are brand new. Cap and rotor are 5 years old with 20k miles