YACT: New plugs = hard start, rough cold idle??

[Armitage]

I replaced the plugs in my Land Cruiser yesterday. Put in Bosch Platinums. This morning when I went out to start it, it started hard ... not real hard, but ussually it's like nothing. The idle was also low & rough ... stalled twice on me, which it never does.

I just rechecked the Bosch site .... I have the right plugs & gapped correctly.

The only other stuff I've done on it recently:

- New aircleaner
- Cleaned battery terminals

I also had to take the pipe from the air cleaner to the throttle body off to get at one of the plugs. Shouldn't matter.

Any ideas?

 

[T2T III]

Are you sure the plug wires are securely attached? Were you careful in pulling off the plug wires so that they were not damaged?

 

[Oger]

Armitage ;

Did it have a rough idle before you changed the plugs ?

 

[Demon-Xanth]

Also, they're in the right order, correct?

 

[awal]

what type of plugs did you have before? WHen I had the plugs on my truck changed I read bad reviews about Bosch Platinum plugs. They were fine for me, but I only had the truck for another 1000 miles befroe I traded it in for a car.

Jap cars tend to be NGK...

 

[FoBoT]

- double make sure you put them back on in the correct order

- sometimes just taking off the wires will crack/break some of the conductors and you have to replace the wires

 

[Armitage]

Old ones were NGK. Idle was fine.
Definitely got the order right on the wires. They're in looms, and you can't reach the next plug with the previous wire, and I only took off one at a time. Some of them came off kinda hard, but I was careful to only pull on the boot.

Another note ... there's a cable that runs across the top of the air intake system to the throttle body. Probably the throttle cable. I had to pull on that a bit to get the intake pipe out of the way. Maybe I tweaked the throttle setting a bit?

Those Bosch Platinums are funky spark plugs. Never saw one before.

 

[Pliablemoose]

I really like the Bosch plugs, priced right & perform well.

Suspect you've inadvertantly messed up the plug wires, after a few years they can look fine, but become non-funtional after they're flexed a bit.

Also, you need to put the dielectric silicone on the plugs.

Have you replaced the rotor & cap? (not sure if your L/C has them), don't know what year you have...

 

[Armitage]

Originally posted by: Pliablemoose
I really like the Bosch plugs, priced right & perform well.

Suspect you've inadvertantly messed up the plug wires, after a few years they can look fine, but become non-funtional after they're flexed a bit.

Yea,the wires look fine. I watched it running in the dark last night and didn't see any arcing & such, which I've heard can happen when they're on their last legs.

Also, you need to put the dielectric silicone on the plugs.

Yep, did that.

Have you replaced the rotor & cap? (not sure if your L/C has them), don't know what year you have...

Nope ... but maybe that & new wires will be next on the list. It's a 93 FZJ80, 4.5L straight 6

 

[KEV1N]

Maybe double check the airflow sensors you may have unplugged when detaching the airbox from the throttle body? Maybe it's getting an incorrect reading, or you have a leak, causing you to not get enough fuel? Just a guess

 

[Armitage]

Originally posted by: KEV1N
Maybe double check the airflow sensors you may have unplugged when detaching the airbox from the throttle body? Maybe it's getting an incorrect reading, or you have a leak, causing you to not get enough fuel? Just a guess

Didn't unplug them, but that's a good idea. I'll check that they didn't get pulled loose, although I suspect that would trigger a check engine light.

 

[lightpants]

Originally posted by: Armitage
I replaced the plugs in my Land Cruiser yesterday. Put in Bosch Platinums. This morning when I went out to start it, it started hard ... not real hard, but usually it's like nothing. The idle was also low & rough ... stalled twice on me, which it never does.

I just rechecked the Bosch site .... I have the right plugs & gapped correctly.

The only other stuff I've done on it recently:

- New aircleaner
- Cleaned battery terminals

I also had to take the pipe from the air cleaner to the throttle body off to get at one of the plugs. Shouldn't matter.

Any ideas?

Change out the POS Bosch Platinum plugs and it will fix your problem. I have seen this same problem many times before.
Did you disconnect the battery when you cleaned the battery terminals? If so, your car might have to relearn the idle settings. How many miles do you have on the car?
However, I would change those plugs asap.

 

[Crucial]

If the pipe to the aircleaner is rubber you might not have gotten it on all the way or the bottom edge might have folded over causing a vacuum leak. Recheck this as well.

 

[Armitage]

Originally posted by: lightpants

Originally posted by: Armitage
I replaced the plugs in my Land Cruiser yesterday. Put in Bosch Platinums. This morning when I went out to start it, it started hard ... not real hard, but usually it's like nothing. The idle was also low & rough ... stalled twice on me, which it never does.

I just rechecked the Bosch site .... I have the right plugs & gapped correctly.

The only other stuff I've done on it recently:

- New aircleaner
- Cleaned battery terminals

I also had to take the pipe from the air cleaner to the throttle body off to get at one of the plugs. Shouldn't matter.

Any ideas?

Change out the POS Bosch Platinum plugs and it will fix your problem. I have seen this same problem many times before.
Did you disconnect the battery when you cleaned the battery terminals? If so, your car might have to relearn the idle settings. How many miles do you have on the car?
However, I would change those plugs asap.

Yea, battery was disconnected. Which caused it's own PITA (see my car alarm thread from yesterday). We'll see how it starts tomorrow.

 

[rezinn]

If you gapped the plugs that might be the problem. You aren't supposed to. They have little platinum electrodes embedded in porcelain, but supposedly you can mess them up by gapping them anyway.

I've run bosch platinum in my car for years, they're the only plugs that fit under my headers without burning my spark plug boots. You might just have the wrong application for your car too (heat range).

 

[Armitage]

Originally posted by: rezinn
If you gapped the plugs that might be the problem. You aren't supposed to. They have little platinum electrodes embedded in porcelain, but supposedly you can mess them up by gapping them anyway.

I've run bosch platinum in my car for years, they're the only plugs that fit under my headers without burning my spark plug boots. You might just have the wrong application for your car too (heat range).

When I looked at the Bosch site, there were some that were "pre-gapped", and others that you have to gap manually. I have the latter, and they were way out ... the manual (& the Bosch site) calls for .032, and they were probably twice that.

 

[TechnoKid]

I bet if you put in NGK v-powers your problem would go away. Coppers performs better than platinum, they just don't last as long, so you end up having to replace the coppers every 15-30k instead of every 45-80k with platinums. And if you think that plats really last that much longer than copper, take a look at the plat plugs when they are supposedly due (even 1/2 to 2/3) for a change, you'll be suprised at how much they've worn.

Also, double check the gap. I've never heard of a platinum plug that you can or are suppose to gap.

 

[EyeMWing]

Bosch plats like to explode under boost. Of course, your land cruiser isn't much of a candidate for THAT but they're still junk.

 

[NutBucket]

The solution to your problem is to run OEM plugs. I know my Honda didn't like the Bosch Plats I had in there. Went back to OEM NGKs and it ran much better.

 

[Ornery]

I sent my plugs back to Bosch after 8 months, for my money back. THEY SUCK! Went with the Motorcraft platinums that I should have put in there in the first place.

 

[StageLeft]

Somebody on maxima.org today had replaced their NGK stock platinum plugs with bosche 4-tip and were complaining about a rough idle. They were not sure that the plugs were to cause, but other people were saying that they probably were, and to go with NGK. Fact is if you changed your plugs properly and nothing else and now your idle is rough, your new plugs suck

 

[BatmanNate]

I wouldn't touch Bosch Plats in my Toyota, I've heard too many bad things about them from every Toyota owner I've talked to, particularly with turbocharged motors.

 

[T2T III]

Originally posted by: Ornery
I sent my plugs back to Bosch after 8 months, for my money back. THEY SUCK! Went with the Motorcraft platinums that I should have put in there in the first place.

I put Autolite Double Platinum plugs in my Ford during the plug change that I performed a few months back. They were about $4.00 each, but well worth the price.

 

[Ornery]

I bought dual platinums, by Motorcraft at close to $4.00 each. They would have been cheaper at Walmart, but they were out of stock at both locations. I ended up getting 4 at NAPA and 4 at Advance.

 

[Eli]

Did you gap them? Oh, yeah.

Hmm... That's a strange one..

This thread surprises me. I didn't really realize that the brand of plug could make such a difference. I mean, we've been using the same basic design for the last 100 years... lol