I been having some big time hesitation issues at 4500 to 5000k in 3rd and 4th gear. The only mod is a cpe nano, however recently I replaced the spark plugs with bosch iridiums. I've been getting super good gas milage (around 27mpg per tank) however I think this may be the cause of the stuttering. At first I thought it was a boost leak, but I don't think so because it doesn't do it all the time. Anyone else run into these problems. The car has almost 65k on it and I haven't had any complaints or issues yet.
Hesitation at 4500 to 5k
- Thread starter DynoBunny
- Start date
A little investigation info:
Bosch plug 4515 should have this number on the plug - HGR8MQI
If it does, it is my understanding that the 8 represents heat range 8 under Bosch's system. See attached chart to decypher Bosch's numbering code.
Then consult attached cross-reference chart.
If I am reading the chart correctly, that would be equivalent of an NGK 5 or a Denso 16.
If that is right, the Bosch plug is one to one and a half heat ranges too hot. This could be the cause of your problem.
Also, there is data to suggest that platinum (even in a blend with iridium, as with your choice) is not a good choice for high cylinder pressure engines, such as cars running nitrous or turbocharged cars with high boost and high compression ratio and direct fuel injection.
The preferred plug would have an iridium tip, but would have the core of that tip and the ground electrode made of pure copper which is better at transferring heat, rather than holding it, as platinum does.
I don't know if going to a proper heat range Bosch plug will solve your problem, but it would seem to me that you would be better with either stock plugs or the NGK or Denso equivalent with iridium tip on copper core and a solid copper single ground electrode.
Bosch plug 4515 should have this number on the plug - HGR8MQI
If it does, it is my understanding that the 8 represents heat range 8 under Bosch's system. See attached chart to decypher Bosch's numbering code.
Then consult attached cross-reference chart.
If I am reading the chart correctly, that would be equivalent of an NGK 5 or a Denso 16.
If that is right, the Bosch plug is one to one and a half heat ranges too hot. This could be the cause of your problem.
Also, there is data to suggest that platinum (even in a blend with iridium, as with your choice) is not a good choice for high cylinder pressure engines, such as cars running nitrous or turbocharged cars with high boost and high compression ratio and direct fuel injection.
The preferred plug would have an iridium tip, but would have the core of that tip and the ground electrode made of pure copper which is better at transferring heat, rather than holding it, as platinum does.
I don't know if going to a proper heat range Bosch plug will solve your problem, but it would seem to me that you would be better with either stock plugs or the NGK or Denso equivalent with iridium tip on copper core and a solid copper single ground electrode.
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Yea, I decided these ran like s*** and took them out today, I took them back to autozone and ordered some denso itv22s from pg. Right now the old fomocos are back in and it already runs a lot better. Other then the good gas milage those bosch plugs are junk.
bradboyd80
Member
- :
- '12 Velocity Red MS3
If I'm not mistaken, the ITV22's are a step colder than stock also.
Very good info to know.
Yes one step colder, the bosch plugs were a step hotter. I plan on doing some other mods in the future so I figured I would get the densos for now.
