Thread: Hard Start and Backfire after new plugs

Alright, so I did a little tune up today...

I got some new plugs to start with, and I did the sidegap and index technique with them. I also adjusted the TPS up to 0.41 V (couldn't get it higher), cleaned the air filter, and checked the codes.

The issue here is that while the car feels (I think!) a lot better to drive and seems to have regained some of its power, it has a harder time starting and I can hear a lot of very slight (not loud) backfires when on engine braking deceleration.

Anyone know what might cause this? I am not 100% sure it didn't backfire before, since I wasn't paying attention to it then. But I am almost positive it is harder to start up now.

The plugs in it before were BRK5E IX (irridium). I replaced them with (uggh) bosch platinums =( because the screen at advanced auto said the bosch irridiums were not gappable, and you need to reduce gap when side gapping.

Anyways, could this be the fault of side gapping this type of plug? It is different than a regular plug as the ceramic covers all but the tip. Here's a comparison pic. The platinum is on the right and normal on left. It seems to run just fine, even better than before. Just the hard starts and backfires concern me.

Haven't been able to check the timing in a while.

Definitely check the timing ASAP. What did you set the plug gap at?

i was always told that bosch and nissan = bad things.

Perhaps unrelated but I had hard starts and backfires when my car had a intake plenup to collector leak.

Won't be able to for a while, but I plan to haha. They are at 0.03 in right now. Thought about going lower, but chose not to.



Well, at least they weren't the autolites. I know I should've got the NGK grrr.



Pretty sure I'm solid on my intake setup. I've only got the pipe and 1 hose lol!

On a side note, it started pretty easily today. May have been from something stupid like starting it a lot yesterday haha. Still does the backfiring thing though.

Noticed something else today though. I was playing with the SAFC a bit, and noticed that it doesn't seem to change anything. I am positive it's hooked up right, since the car runs like it has no MAF if you unplug it. Anyway, it's possible my fuel filter could be clogged up since my WB tells me I'm always running lean no matter what. =/

I don't know. Sensor is calibrated, but it just seems so wrong to be running 19 or 20:1 AFR at WOT as I go all the way up to redline. Having a hard time believing it's correct!

Lots of stuff to do, ugh.

Good thing the single electrode bosch's are cheap. Go get some NGK's and call it a day , they cost under $2 a plug too.

How were you adjusting the TPS btw?

does the car kinda cound like its choking itssself off? normally hard starts, having the car kinda choke itssself off, hesitation, all that is more or less related to bad fuel filter/maybe pump

Volt meter on the back of plug. It was at 0.27 =OOOO Got it up to 0.42 V but it's maxed out now haha. Still below spec. =(

I may have to get some.



Just seems to "fire" less lol I guess you could say choking. But now I'm not so sure because it seemed alright today.

Here's another strange thing which points to the plugs being at fault maybe:

I noticed on decelleration engine braking my AFR's were richer than 20, which is really odd since they normally max out the gauge on lean (I thought the injectors did not fire on decel???). This JUST started happening for sure. Seems like one of the plugs could be crappy or something and not burning the fuel well on decel which could cause both backfire and low AFR readings. Dunno, anyone have thoughts about that?

I am still very confused as to why I just redlined my car and was at 19:1 AFR!!! Grrrrr.

Do you still have your old plugs? Put those suckers in and try driving the car.

Oh I forgot to mention about iridium's and platinum's. I wonder how they would perform side gaped, if they weren't so expensive I probably would hid the dyno with a sidegapped and regular pair.

Yes. I would find side-gapping the shrouded electrode spark plug to be almost impossible to any specific distance with regular tools.