Hey Everyone,
Hope you can help me out, thanks in advance. I have a 98 tacoma, 4 cyl., 2.7L. The other weekend I replaced the plugs, fuel filter, starter contact rebuild, cleaned the MAF sensor. It ran great for a few days and then rough again when idling. Cleaned the throttle body (got in there with a rag and cleaner), did not take the body off, just the intake hose closest to it. Also recleaned the MAF. Ran good again for 2 days. Now it is running rough again at idle (lots of vibration, can feel it in the stick) and the starts aren't the smoothest. Check engine light back on. Any ideas? Seems like MPG has gone down too. All of these problems started with the new plugs, fuel filter, starter solenoid rebuild, MAF cleaning. Any help would be great, bring it on people. Thanks

 

What's the engine code that it threw? What did you use to clean the MAF?

 

I don't have a handheld, so I don't know the code that was thrown. Used MAF cleaner, I think CDC makes it. But it was specifically for that.

 

Get the code read at autozone or kragen, etc.. and we will be able to help out more.

 

What plugs did you use to replace the old ones with?
This a key factor.
Really sounds like you did not use a dual ground performance plug!
NGK dual grounds??????????????

 

It's sounds like the plugs. The dual ground NGKs or Densos are the only plugs you should ever use in these engines, and even if those are what you used, you might want to pull them all back out anyways and start over. I'll bet there's a bad connection somewhere. Maybe one of the wires isn't on all the way cuz it sounds like your describing an intermittent miss. I'll bet the CEL will be a P0301 - P0306.

BTW, when you cleaned the MAF did you just lightly spray the wires and let them dry, or did you scrub the wires w/ a q-tip or something? Touching the wires w/ anything can damage them cuz they're very sensitive.

 

Hey guys,
Here are the codes that were thrown:
P0300 random misfire detected
P0301 cylinder 1 misfire
P0304 cylinder 4 misfire
P0110 intake air temp sensor 1 circuit

I put in the NGK G-power plugs. Those are the platinums, is that OK? Good call brian2sun with the codes. I think all of these codes are possibly linked to the MAF, what do you think. I can get one for $100 from toyota, it might be worth trying out and if that doesn't do the trick, thank run through the plugs and wires, right? I only sprayed the MAF sensor with the cleaner, no touching with anything. I did spray it point blank though, could that of dislodged something? Thanks fellas, again, any help would be great and advice useful.

 

Here's another thought. When I took out the plugs to replace them, a gasket from the top of cylinder 1's plug tube had fallen to the bottom of the tube and melted onto the plug head below during use. Is it possible that the loss of this gasket is causing insulating issues in the tube and electrical interference? Do you know the gasket I am talking about it sits right at the top of the plug port around the perimeter of the tube.

 

ok go out and look at your truck do the #1 and #4 cyl.s share the same coil? I ask because I have a 6cyl.
and mine of course is different.
the next question is did you use Di-Electric grease? I found this to be a big issue on my truck at first.
since I have started using Di-Electric I have a lot less problems. pull the plug wire or coil take a tube of the grease and squeeze some in the down tube. be liberal a big tube will last a while get the big tube.
it costs about $2 more than the little tube.
as for the temp sensor that is the one on the side of the maf.
did you clean this well? may be time for a new one.
and replace the gaskets at the tubes both ends they are fairly cheap like $10 or so.
this could not effect cyl.4 but will stop the oil from spilling in to the tubes and creating a hell of a mess.
actually the only way this could interfere is if there is some thing stopping a ground of the plugs and causing mis fire.

 

#1 and #4 do share the same coil. Think this could be it?

 

This definitely could be. now take the coils and give them a good dose of Di-Electric switch them and see if the code stays. don't forget to dose the wires with Di-Electric!
if the code stays at 1&4 it is plugs or igniter, and if it moves it is coil specific.
I have taken my coil and pulled the spring out of the drop tube and stretched it then got it back in some how I think I used a long skinny flat head to push it back in the tube so that it clicked.
Remember that you NEED TO USE DI-ELECTRIC!!!! this is essential in our trucks.
I Di-Electric all electrical connections that I take apart especially Coil, Plug Wires, and Battery Terminals.

elaboration
When I say igniter I mean either the Igniter output or the wires between the igniter and coils. Di-electric all contacts here your problem may just disappear. Wouldn't be the first time.

 

OK, so how and what do I apply the di-electric too?

 

I think you're on the right track now - Did those platinum plugs have 2 grounds on the plug or just one? NGK BKR5EKB-11 is the part # for the stock NGK plugs. Re-do the plugs and wires if the coils check out good and between the 2 possibilities, I think it'll be fixed. x2 on the di-electric grease - I've also had some problems in the past when not using it.

 

all electrical contacts. the down tubes just put a generous amount in the down tube and re-install.
the plugs both from the igniter and to the plug wire put some on the igniter plug and plug in spark wire plug do the wire side on the contact side.
try to clean off any corrosion if you can't just di-electric and connect pull the battery neg. wire and clear the codes. drive and see what happens.

 

see your in that know as well
no di-electric is like !!!!

and for future readers DI-ELECTRIC use it alot!!!!!!!!!!!!!!1

 

Squeeze the di-electric into the female ends of the wires and coil boots and/or the male end of the spark plugs. It's good to put a little on all the electrical connections too, just open them up, squirt some grease and re-connect.

 

Really, I've been reading not to put it on electrical connections rather it should be put on the boots and insulators of the connections. So you are saying to put it right in the connections?

 

One more thing, do you know if you can swap the wires on the coils instead of undoing the coils and swapping those? Or would this cause the truck to fire out of sync?

 

Yes I do it all the time. basically take a connector off the coil from the igniter on the plug apply the grease then plug back in.The grease will not spoil the contact because the metal touches, but the grease will coat the metal preventing corrosion which is the objective!
any wires that have flat round connectors that you screw down with a nut on clean the bolt and connector, wipe di-electric on the bolt and connector removing excess"coat both parts "coat"" reconnect then apply more di-electric to the top preventing air from getting to it.
the thing is that you need to put di-electric in the drop tube so you have to pull it.
switching the coils will tell you if the misfire changes"this will tell you if it is this coil"
sure you can try to short cut it but it will be more frustrating. and yes just switching the wires will make a misfire due to wrong fire order.

trust me and just do the expanded version I find every time I try to short cut some thing especially during diagnostics that there is more frustration in the end.

Kinda like testing the Cam and crank position sensors on DC rather than AC it sends out an ac signal and dc test does not test accurately.
on dc it will jump possitive negative and ac will give you a volt reading more like .56,0,.57,0,.58,0,etc.......

 

I totally agree w/ eddie, don't shortcut - it'll usually just lead to more questions and more time chasing your tail. Keep ruling things out w/ as few variables as possible.