Bosch Platinum plugs

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1BadDodge71

1BadDodge71

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My Duster 360 has been misfiring really bad,mostly while crusing.I know I need new plug wires but decided to remove a plug to look at them.I had no clue as to what brand they were since I didnt build the motor but saw they are Bosch Platinum.Can this be my problem?I read never to use these plugs in our motors.Anyway,I plan on replacing them with Autolites tomorrow.
 
Same thing happening to our 440. Lots of missing during cruise. No real missing during load acceleration. Plugs were totally covered with brown plastic looking crap.
I generally think minute electrode plugs will foul over quickly on old designed engines.
The plugs (ngk v groove) were probably fouled by the fuel additive I was running all the time. Plugs had about 2k on them. Also the motor is 37 years old and only has 25k on it, so rings may be weak. Also, the plug boots on the plugs were cracked to hell. Here is what I did. I scraped the oxidation off the pins inside the dist cap, scraped the rotor contacts, put autolite coppers in the motor, cut and re routed the plug wires with some autozone plastic plug wire clips. New plug wire boots on the plug end of the plug wire. Runs perfect.
 
yeah,im not a huge fan of fancy plugs.I just put a new dist. cap & rotor also.I needto time it too but it sounds like it has a radical cam also so i dont know where to set the timing,thanks for the reply
 
Bosch Platinum are probably some of the worst plugs in existence. After only a short time they begin to allow compression to be lost through the plug. AC Delco are probably some of the better by far.
 
I've had great luck with Bosch Platinum plugs ( but I run the Plat 2 in my eco car and plat 4 in my 340) Not a problem with them. I would try using the Plat 2 plug and see what they do for you.
 
Autolites are all i run in my vehicles...autolite race in my duster with great results,not a fan of Bosch....
 
Running Bosch Plats in mine. No issues and most of my time is spent at cruise speed. Since plugs aren't easy to change with a 440 I wanted a low maintenance plug. While I wouldn't rule them out, I'd look for other reasons for the miss.
 
Check your wires Plat plugs will take more voltage to fire and tend to wear out wires a bit quicker. Might be a coil issue also. I only use plats in wifes mini van where the back three plugs are hard to get to. For my dart I like plain old copper plugs changed once a year wheather it needs it or not.
 
Agh,I changed the plugs and plug wires,now the damn thing will not start!:cussing::banghead:
Im sure I got the firing order right.Its 1-8-4-3-6-5-7-2,rotating clockwise,right?I dont understand.It fired up great before I changed them.I guess I shouldve left them alone huh ?
 
A maybe data point.

My 2.4L Plymouth started missing on hard acceleration. After changing plug wires and coil pack with no luck, I changed the platinum plugs (Bosch I recall) to regular types. Fixed it. I suspected the thin platinum wires broke internally. Plugs were clean. I recall streaks of blowby on the ceramic shell (mentioned above).

The problem returned after several years, so I followed a Chrysler TSB for 2.4L Turbos and lowered the gap (0.060" to 0.050" I recall), which fixed it. Perhaps the ignition circuit degrades over time (mentioned above). The van was also in an accident so my engine controller board could have a crack.

Re Bosch, I have a Mercedes diesel and most owners say Bosch glow plugs are the worst. I try to get Beck-Arnley.
 
I have had terrrrible luck with Bosch plugs. Put them in a 350 Chevy once and it wouldn't start. Took them back out and put in AC Delco and it ran like a kitten again.
 
Ok,idk why but for some reason,I put the bosch platinums back in and the car still wont start.The Autolites I bought for it were wet with fuel,as if they were not getting spark.I even swapped coils,still nothing.This car started last night just fine before I did this this morning.Im really really questioning the plug wires I bought from Autozone.Im positive I have the firing order correct.I did a resistance test.The new wire had 9.45 kilo ohms,the older wire had 7.03 k ohms (?)it popped while attemping to start it,and I didnt move the dizzy at all.This is weird.
 
1BadDodge71 said:
Ok,idk why but for some reason,I put the bosch platinums back in and the car still wont start.The Autolites I bought for it were wet with fuel,as if they were not getting spark.I even swapped coils,still nothing.This car started last night just fine before I did this this morning.Im really really questioning the plug wires I bought from Autozone.Im positive I have the firing order correct.I did a resistance test.The new wire had 9.45 kilo ohms,the older wire had 7.03 k ohms (?)it popped while attemping to start it,and I didnt move the dizzy at all.This is weird.
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Are you sure you routed the plug wires to the correct plug?
 
Well,I took off the dist. cap and found the pick-up coil was loose and rubbing on the reluctor,so I gapped it with a brass gauge and it fired up!Got to love when this happens,lol.But it seems to run MUCH better with the new wires and plugs.Im going to try and post a video later.
 
The pick up coil was probably the culprit right from the start, and not the plugs.
AC's use to crack the porcelain and would slide down and cover the electrode. Take them out and look at them and it was fine. Then you turn them over and find the problem.
The NGK U groove are just relabeled Nippondenso plugs. They work well. I never had a problem with the Bosch Platinum, But if I recall, they were designed for a hotter spark (HEI system, or better coil).
 
prodart340 said:
I run the bosch platinums with a msd 6al and haven't had a problem in years
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Im keeping the Boschs just incase Im sure there is really nothing seriously wrong with them,its just Ive pretty much replaced everything on the motor since installing it(like new oil,oil filter,fuel filter,dist.cap & rotor etc),might as well put fresh plugs and wires.Besides,I have no clue as to how old these plugs are.:profilel:
 
After working in the auto repair industry for 14 years, I'd agree with the folks who said they are junk. They ARE JUNK. I wouldn't put one in my lawnmower.

I once pulled 6 of them out of a 4.0L Jeep that had a misfire. Five of the plugs had ALL four of the ground straps completely missing!! Some had the porcelain missing completely. Where they went, and how the vehicle even ran, I'll never know. Probably some went out the exhaust, and I'm sure some are embedded into the piston tops! Put the correct plug in the vehicle ($1.39 Champion), and it ran fine.

Had a hyundai one time with a single cylinder misfire, pulled the plug on that cyl. (bosch platinum) and there was nothing left of it. The complaint from the customer was "Check for rod knock". Put 4 of the correct spark plugs in the vehicle (NGK), and it ran better than ever. Customer thought they were going to be paying for an engine overhaul with as bad as it ran/sounded.

Somewhat off topic, since this post is related to our older mopars, but on newer cars ('96-up), you must use the same brand of plug that came out of the vehicle. Otherwise, you'll more than likely get to know the fault code P0300 (multiple cylinder misfire) very well ...
 
Duster346 said:
After working in the auto repair industry for 14 years, I'd agree with the folks who said they are junk. They ARE JUNK. I wouldn't put one in my lawnmower.

I once pulled 6 of them out of a 4.0L Jeep that had a misfire. Five of the plugs had ALL four of the ground straps completely missing!! Some had the porcelain missing completely. Where they went, and how the vehicle even ran, I'll never know. Probably some went out the exhaust, and I'm sure some are embedded into the piston tops! Put the correct plug in the vehicle ($1.39 Champion), and it ran fine.

Had a hyundai one time with a single cylinder misfire, pulled the plug on that cyl. (bosch platinum) and there was nothing left of it. The complaint from the customer was "Check for rod knock". Put 4 of the correct spark plugs in the vehicle (NGK), and it ran better than ever. Customer thought they were going to be paying for an engine overhaul with as bad as it ran/sounded.

Somewhat off topic, since this post is related to our older mopars, but on newer cars ('96-up), you must use the same brand of plug that came out of the vehicle. Otherwise, you'll more than likely get to know the fault code P0300 (multiple cylinder misfire) very well ...
Click to expand...

yah,and they are pricey.I changed the plugs in my moms 2000 monte carlo,damn things were like $5 a plug.
 
Yup,champions or autolites seem to work best in my mopars chineese plugs work best in cars of the same brand.but that`s just my opinion on that.
 
Duster346 said:
After working in the auto repair industry for 14 years, I'd agree with the folks who said they are junk. They ARE JUNK. I wouldn't put one in my lawnmower.

I once pulled 6 of them out of a 4.0L Jeep that had a misfire. Five of the plugs had ALL four of the ground straps completely missing!! Some had the porcelain missing completely. Where they went, and how the vehicle even ran, I'll never know. Probably some went out the exhaust, and I'm sure some are embedded into the piston tops! Put the correct plug in the vehicle ($1.39 Champion), and it ran fine.

Had a hyundai one time with a single cylinder misfire, pulled the plug on that cyl. (bosch platinum) and there was nothing left of it. The complaint from the customer was "Check for rod knock". Put 4 of the correct spark plugs in the vehicle (NGK), and it ran better than ever. Customer thought they were going to be paying for an engine overhaul with as bad as it ran/sounded.

Somewhat off topic, since this post is related to our older mopars, but on newer cars ('96-up), you must use the same brand of plug that came out of the vehicle. Otherwise, you'll more than likely get to know the fault code P0300 (multiple cylinder misfire) very well ...
Click to expand...

The only reason I ever found for the ground straps to be melted off, is when they weren't tightened enough. Will melt the ends of them off every time, regardless of plug type/manufacturer.
 
What kind of spark plugs you suggest for nearly stock 318 with orange box and copper wires (with no resistance)?
 
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