idle missfire??

[QUICK STORM]

Re: idle missfire??

yes that is the sensor for the gauge the one in the passenger side head w/ green wire.

the coolant temp sensor for the ecm is on the lower intake manifold near the thermostat housing.

have you had your leak down, compression and vacuum test done yet?

 

[Don W.]

Re: idle missfire??

Thanks Brandon, I had 'em backwards. Anyway, Datamaster should be showing actual eng temp. roughly based on what t-stat is installed. Per the manual sensor ohms are 450 @ 160* and 3,400 @ 70*. I admit I'm 100% clear here but I gather that the sensors themselves are the same. Wondering out loud, are the two circuits completely separate? One for the ECM and one for the gauge?

 

[gjp]

Re: idle missfire??

dm shows temp @ 168*
If it idles for long it goes up to 185*
missing starts @ around 165+
if I stop and let the engine heat soak it gets worse on re-start. the more it runs the worse it gets. If the ecu see's 170* it should set fuel for that. The stock guage shows 140. The warmer it gets it realy does not miss more but just harder.

MY complete list of mods and work I did:

past 2 weeks;
ign. module
distributor
ngk ur5
taylor 8mm wires
cap
rotor
oil switch
heater core
coil
re-did ground on engine (behind alt, firewall on driver side head)
checked cat.

Past 3 months;
new 50# injectors
3 bar map sensor
Phil long chip
Silicone vacuum lines
TEC
compression test (150-162)
T.B. cleaned, bearings added and opened to 52mm
Air foil
new IAC
160* stat
purple wire fix
1996 454 starter
optima red top battery


Last summer;
new atr exhaust w/hf cat
O2 sensor
fuel pump 255lpm
Greedy boost control
greedy boost guage
Removed boost solenoid

Other mods;
KB CAI
battery relocate in bed
ATR aux intercooler w/ HF pump
rebuilt trans from GN shop with strip build and a 2800 stall

As you can see a lot has been done and still it misses. What have I missed

Leakdown test will be this week as speedmerchant was packed last week. Thanks again to all !!!!

 

[Don W.]

Re: idle missfire??

Sure would like to see and hear this thing. Not that I could offer any magic. Hope to see you at Tom's. Maybe that collective brain trust can help some.

 

[gjp]

Re: idle missfire??

I hope to have it fixed by then
Next chance I get I will do a video of it. The funny thing is even with the mising it still runs strong. The engine skips a beat up till 2000 rpm above that either the missing is gone or I just cant hear it no more. At 1500 rpm you can feel the truck shake every seccond or so as it misses. Again none of this is pressent when cold.

 

[willyson]

Re: idle missfire??

i had the same symptoms as you - it would idle terrible and stutter on acceration until ~2000rpms and then absolutely fly. i had the intake manifold/top end cleaned out (he used the whole can) and it corrected my problem. reading this post im not sure it would do any good, but its just a thought. hope this helps.

 

[gjp]

Re: idle missfire??

Thanks, but I did to a top end cleaning. The funny thing is it got worse right after that.

Nice Sy BTW. How is the dual exhaust done on that. I like the look of 2 pipes. I am thinking about a "Y" after the Cat with no muffler???

 

[willyson]

Re: idle missfire??

Thanks, and I hope you solve your dilemma.

I believe it is the Y after the cat. I have crawled under it when it was on the lift and if I remember correctly, the pipes come together at the cat and pull apart after a muffler. Not sure about the muffler, I think it has one though. It was already installed when I purchased it, but I like it because it gives a more muscle feel to the truck. I'll check with the previous owner and see if its a custom job or bolt-on and get back with ya.

 

[gjp]

Re: idle missfire??

Thanks. my truck is going to see a pro on thursday. Hopefully it gets fixed. for 125$ an hour it better get fixed fast.!

 

[Don W.]

Re: idle missfire??

The more I see them twin pipes the more I like them. I was thinking about this but now it's a done deal. Just gota come up with the $$. Sharp looking truck.

 

[gjp]

Re: idle missfire??

Got my truck back today. so far it runs great. better then ever. Only time will tell if its fixed.
Well Guys it was a mix of a few things. 1st my AFPR was bad, 2nd My fuel filter was FUBAR. 3rd he said what made the biggest improvement was lowering my fuel pressure??? Phil said to run 45psi. QS told me once to try 40psi. Nothing helped. He dropped it down to 32psi and it runs great???WTF. I will run a DM tomorow night to make sure everything looks ok. Would I hurt the truck If I run at that FP??? If the dm shows my o2#'s are gook should I just go with it.??

 

[QUICK STORM]

Re: idle missfire??

Got my truck back today. so far it runs great. better then ever. Only time will tell if its fixed.
Well Guys it was a mix of a few things. 1st my AFPR was bad, 2nd My fuel filter was FUBAR. 3rd he said what made the biggest improvement was lowering my fuel pressure??? Phil said to run 45psi. QS told me once to try 40psi. Nothing helped. He dropped it down to 32psi and it runs great???WTF. I will run a DM tomorow night to make sure everything looks ok. Would I hurt the truck If I run at that FP??? If the dm shows my o2#'s are gook should I just go with it.??

great, glad to hear you got it going good, its kinda hard to diagnose over the internet, it definately helps to have the truck in front of you. run DM and if you get knock, just raise the FP slightly until your truck likes it. a clogged fuel filter will help in reduction of flow so you were trying to compensate by more FP, basically trying to push a square thru a circle, you know. and the fact that the regulator was bad could have been your off idle stumble, basically the truck going full rich, bogging the motor down, but unoticeable at higher RPMs. can't wait to see your truck at toms.

 

[gjp]

Re: idle missfire??

Checked the FP. he set it at 36psi with no vacuum. It runs good and so far no sign of missing. But I will give it a few weeks before I say its fixed. . Last time I thought I fixed it and it came back after 45min of driving. I have yet to drive it that much so time will tell. If my o2 looks good I will leave it at 36psi. Thinking now of my next mod. wideband o2 is top of the list. Is it worth getting for the small amount of mods I have. Looking at the plx m-300???

 

[QUICK STORM]

Re: idle missfire??

i just got the r-500, can't wait to install

 

[gjp]

Re: idle missfire??

QS how is that front shaft.? is it a strait bolt on.? will your Ty be running for Tom's party?

 

[QUICK STORM]

Re: idle missfire??

front shaft is sitting in my room, should bolt right in though

my ty should be running by toms, i WILL be installing it next weekend

 

[gjp]

Re: idle missfire??

SWEET!! About what HP will you be running? is there a post of your build and who did the motor?

 

[QUICK STORM]

Re: idle missfire??

well, i hope to get about the same numbers as jjorgenson, so around 600hp will be sweet.

click the build sheet in my sig for deatils

 

[gjp]

Re: idle missfire??

I took it out. I got a lot of KR.(12* spike then it dropped to 5*) o2 volts were 980 at WOT. engine temp 166. ia temp 93. All 4 time I got into boost I had KR right at 10 psi. I was maxing at 16.7 psi. Also the lower the o2 volts were the less KR I had. Truck feels strong. I pulled next to a late 90's mustang GT. I ate him up. I was running strait 91 oct. I got the typical 2* spike at shifts. I have the stock kr sensor. Should I replace it. torque it to ?? also what size socket it it??

 

[gjp]

Re: idle missfire??

Is this a good price Q.S.
http://cgi.ebay.com/ebaymotors/PLX-...categoryZ33742QQihZ019QQitemZ8072611480QQrdZ1
or
this one http://cgi.ebay.com/ebaymotors/PLX-...ewItemQQcategoryZ38650QQitemZ8073046252QQrdZ1

Think its worth it for me. I think my KR is comming from the low FP. The guy said at 45psi even with the new AFPR and filter He still heard it missing. Its at 36psi. I will turn it up 2 psi at a time and see what happends to my KR. I also have the ur5's in right now. Might go back to Ur6's. I did not hear it knocking but I got as high as 14* of KR. OUCH!! Does not sound like false KR because it does not knock in neutral and only knocks above 10psi. In fact all three times it knocked right at 10.2-10.4 psi.