07 apex rtx loads up and backfiring

[nhmm700]

have an 07 rtx that just doesn’t want to run right. Put new plugs in, fresh fuel etc. sled starts right up high idles and then drops down once warmed up. But once it drops down it starts to backfire. Sled will spin up rpms on a stand but doesn’t sound right. Loads and skips at lower end. Have video for someone to help me with. Thanks Dan.

 

[steiner]

Have you tested the exhaust donuts. Get some old gloves or rags and plug the exhaust tips while the sled is running. If it does not die then your trouble is the donuts.
Do you have a fuel mod or ign mod?

 

[nhmm700]

When you say fuel mod or ign mod, are you meaning individual modules or have mods been done to these. Sled is bone stock no mods at all. The backfiring is very pronounced at rear tips can’t seem to feel anything in doughnut area and don’t have any smoke or pressure coming from doughnut slash collar area.

 

[steiner]

Have you plugged the exhaust at the rear tips to see if the donuts are leaking?????

 

[nhmm700]

Ok tried plugging exhaust tonight and it blew the rags right out. So started looking at more. I had put 4 new plugs in it. I removed plugs and found that the two cylinders on mag side of motor are lightly wet and don’t appear to be firing hence probably why I am getting the backfiring. The two plugs on pto side are nice coco brown. So I tried swapping in some other plugs no difference. I swapped coils no difference. So could I have a chaffed wire in harness affecting these two cylinders? Thanks for help guys and gals

 

[nhmm700]

Also I have no codes showing up. I unplugged tps and bypassed tors and those codes popped up immediately. 15, and 84. I plugged back in and codes went away. Is it possible something with injectors or rail?

 

[steiner]

Bad ground blocks can give issues like that.
https://ty4stroke.com/threads/apex-wont-crank-and-no-fuel-pump.83994/

 

[vader2185]

Ok tried plugging exhaust tonight and it blew the rags right out. So started looking at more. I had put 4 new plugs in it. I removed plugs and found that the two cylinders on mag side of motor are lightly wet and don’t appear to be firing hence probably why I am getting the backfiring. The two plugs on pto side are nice coco brown. So I tried swapping in some other plugs no difference. I swapped coils no difference. So could I have a chaffed wire in harness affecting these two cylinders? Thanks for help guys and gals

when you say you plugged them, did you stuff rags in the pipes? If so you will need to hold rags on the pipes by hand until it stalls. If it does not, it is would be your Y pipes and/or donuts. It would be the first place I would look especially if you have no codes. I think its kind of rare for these things to foul plugs. I have not fouled any and have over 11000 miles. Good luck

 

[earthling]

Ok tried plugging exhaust tonight and it blew the rags right out. So started looking at more. I had put 4 new plugs in it. I removed plugs and found that the two cylinders on mag side of motor are lightly wet and don’t appear to be firing hence probably why I am getting the backfiring. The two plugs on pto side are nice coco brown. So I tried swapping in some other plugs no difference. I swapped coils no difference. So could I have a chaffed wire in harness affecting these two cylinders? Thanks for help guys and gals

Pull the plugs, reconnect to the coils and check for individual spark?

 

[nhmm700]

Earthling can I do this like old school with wires? Just lay coil on head and turn over to test for spark individually?

 

[nhmm700]

when you say you plugged them, did you stuff rags in the pipes? If so you will need to hold rags on the pipes by hand until it stalls. If it does not, it is would be your Y pipes and/or donuts. It would be the first place I would look especially if you have no codes. I think its kind of rare for these things to foul plugs. I have not fouled any and have over 11000 miles. Good luck

Yes I plugged with rags and they literally blew out half way across garage. I cannot feel any leaking around head and pipe joints and exhaust doesn’t sound loud or different.

 

[earthling]

Earthling can I do this like old school with wires? Just lay coil on head and turn over to test for spark individually?

yes, throw a plug in the coil so you can see what's happening.

 

[slowride06er]

Yes I plugged with rags and they literally blew out half way across garage. I cannot feel any leaking around head and pipe joints and exhaust doesn’t sound loud or different.

I put welding gloves on when I do this holding rags in my hands I jam rags inside tips not allowing any exhaust to get out the back. If you have no leaks engine will stall and if it doesn't stall and no exhaust is getting out either tail pipe you have a exhaust leak and need to find it.