sparkplug + fuel pump question

aj510 · 18-05-2008, 03:20 PM

Ok so I was having problems with the motor having a bit of a cough when it got to 5000rpm (nissan sr20det).

I figured it might be the pumps as they were only getting 11.00 to 11.5 volts at idle and i'm guessing up high alot less.

I rewired the pumps directly from the battery with a relay to trigger them . Now they are getting 15volts. - is 15 volts too much?

But what has happened as a result of this is that it appears i'm overfuelliing - as it is blowing alot of black smoke - checked the plugs and it's all carbon no oil at all. The plugs haven't been changed for quite some time - probably 9 months and have done atleast an hour or more of idiling whilst working out tuning etc. Also should note that if I take it to 6500rpm there s no miss/cough or anything. Doesn't blow smoke at anytime other than idle and really low revs !1000 - 1500rpm

What gap should I run for an sr20det - 1mm??

Am i right in thinking it is over fuelling or should I think about rings etc???

FAT-245 · 18-05-2008, 03:28 PM

If the ECU Was Tuned for the low Pressure, they would of compensated with the injector duty cycles.

Now that the pumps are getting more voltage, they are pushing more fuel through the injectors when they open.

14.4V Should be the standard Charging voltage, (well this is what ive been told)

All my Electric's run on 15V (when the alternator decides to work) and they do not have an issue, even my Holley Pump runs on it

aj510 · 18-05-2008, 04:38 PM

ECU is custom tuned for the new combo. I'm thinking the plugs are screwed and maybe too cold plugs. I used cheapys as at the time I was chewing through plugs like crazy (sorting out timing etc).

FAT-245 · 18-05-2008, 06:58 PM

Don't think you got what i was saying...

My Brother's Audi had the same issue with his pumps when tuning the car. they were getting 10.7V but after I upgraded all this grounds and Power Feeds they got 14.7 and the car was sputtering and farting.

Turns out the pressure in the Fuel System increased and engine was running rich, we needed to lean it out.

baconson · 03-02-2010, 02:00 PM

please before you do anything, change your fuel filter

fcv85l · 03-05-2010, 08:38 PM

ensure fuel pressure is still set at the original tune pressure and monitor the operation of the fuel pressure reg for correct operation or the tune will be useless

Rhys1600 · 04-05-2010, 09:37 AM

In mine i run Bosch copper BCP 7's gapped down to 0.8mm.
I can get you the exact part number if you like.

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18-05-2008, 03:28 PM	#2 (permalink)
FAT-245 Banned because i am a retard Join Date: Apr 2008 Location: Sydney Ride: Hey Charger...MY ASS! Posts: 3,091	If the ECU Was Tuned for the low Pressure, they would of compensated with the injector duty cycles. Now that the pumps are getting more voltage, they are pushing more fuel through the injectors when they open. 14.4V Should be the standard Charging voltage, (well this is what ive been told) All my Electric's run on 15V (when the alternator decides to work) and they do not have an issue, even my Holley Pump runs on it

18-05-2008, 06:58 PM	#4 (permalink)
FAT-245 Banned because i am a retard Join Date: Apr 2008 Location: Sydney Ride: Hey Charger...MY ASS! Posts: 3,091	Don't think you got what i was saying... My Brother's Audi had the same issue with his pumps when tuning the car. they were getting 10.7V but after I upgraded all this grounds and Power Feeds they got 14.7 and the car was sputtering and farting. Turns out the pressure in the Fuel System increased and engine was running rich, we needed to lean it out.

03-02-2010, 02:00 PM	#5 (permalink)
baconson Newby Join Date: Feb 2010 Location: Queanbeyan NSW Ride: 2009 buell XB12ss, 1988 mazda 323gtx turbo, 14psi, wrx cooler, microtech lt4, HEI Posts: 9	please before you do anything, change your fuel filter

03-05-2010, 08:38 PM	#6 (permalink)
fcv85l Newby Join Date: Sep 2009 Posts: 49	ensure fuel pressure is still set at the original tune pressure and monitor the operation of the fuel pressure reg for correct operation or the tune will be useless

04-05-2010, 09:37 AM	#7 (permalink)
Rhys1600 Newby Join Date: Mar 2010 Location: Penrith Ride: SR'd Datsun 1600 Posts: 10	In mine i run Bosch copper BCP 7's gapped down to 0.8mm. I can get you the exact part number if you like.