Well, i've had my headers in for almost 4 years now and over the last 3 years or so i've been battling the PITA cel PO171. So i've since replaced parts namely, a new MAF sensor, all new oem Denso O2 sensors, all new Denso iridium plugs and have done other maintenance items such as cleaned throttle body, fuel injectors etc etc. The car always ran well but i've always gotten 14 - 15 mpg and this cel would periodically pop up. No vacuum leaks at all...i checked all hoses. Just yesterday I went to my friend's shop and first checked the codes. The PO171 still running behind the scenes. Check this out, long term fuel trim was over +34! The tech said I am dumping a TREMENDOUS amount of fuel and have been for a very long time, he said this figure should be 0 or close to it. He too checked all vacuum hoses and also checked the air intake manifold with some aerosol spray...no leaks. So we threw it up on the lift. I have cracks on both headers almost 3/4 around the pipe along the welds! Unfortunately, because they wrap around the pipe like that he said he cant re-weld while they are on the car. He told me he would take both off, fix and re-install for $250! Sick price! Work is being done next Saturday. I think this is the culprit as these large cracks are pre-O2 sensor, so fresh air is coming in and throwing the readings off.
Hopefully this does the trick and i'll orobably get

 

more performance out of the car and better gas mileage. Btw, these are S&S headers that I bought used that supposedly they were from the 3rd batch; the one without the cracking problems. I'll keep you guys updated. Thanks

 

That sucks. Was it just a single runner on each side or multiple places? Most cracked headers I've seen crack on the pipe near a weld and usually not on the weld itself, unless the weld didn't take good in the first place.

The exhaust flow passing by is pulling in oxygen thru the cracks and giving false reading to o2's, getting this fixed could help mileage a little. I'm surprised your not experiencing any abnormal feeling like missing or lack of power in certain situations if the cracks are that large?

$250 is a good price to take care of it. Unfortunately cracked headers are pretty common with lots of other cars and header brands.

 

I've said a few times. The V8 has more torque so it will be twisting on the headers pretty hard when you stomp on the gas, especially with the mushy motor mounts these cars come with. This will be even worse when coupled with old motor mounts. When you do a hard run, the EGT is probably over 1200-1300F range and the metal is more susceptible to cracking. If you haven't done so, I would suggest you get some new motor mounts. It should reduce the chances of the headers cracking.

 

^^^^ adding some flex sections directly after the merge collectors connection to the rest of the exhaust would also be beneficial in relieving some tension with the motor twist issue.

 

Are there aftermarket motor mounts for our cars? I replaced the motor mounts about 4 years ago with the header install. If the oem ones are too sodt and fragile i'd like to look into alternatives. Any suggestions?

 

I was developing a set of custom polyurethane mounts with a company for the GS300, but there wasn't enough interest so I abandoned the project. The GS4/430 use a different mounting style, and there is even less demand for those lol. You might be able to use a Supra TT aftermarket engine mount as it is angled very similar to the GS4 mount. Only problem is that the GS has two bolts going through the crossmember whereas the Supra only has 1. Maybe with some cutting or shaving, it could be made to fit?

 

i have some, i got them from PPE when i bought his headers. will finally be attempting install in 2 weeks

 

If they are cracked its pretty obvious. You can smell exhaust gas and it will tick under load and you will lose power at the same time

 

I think Megan has some mounts for our cars

 

I think its just for the SC400 guys.

 

How are the PPE headers holding up? Anyone know?

 

what car are you guys talking about is it a 400/430 or a 300? lol

 

they do indeed only make them for the SC



although they look very similar to the GS ones and we use the same motor (well gs400/sc400 do) i dunno if these would fit. i guess if sewells part #'s match for the SC400 and the GS400 they would.....although i think the gs430 uses the same motor mounts as the gs400 but im not 100% sure without looking (i know the tranny mount is the same for the GS v8's)

havent heard any complaints, im 99% for sure installing mine this next weekend

S&S and PPE only made/make headers for the v8 gs models (LS430,SC400/430,GS400/GS430)

 

Can u describe these and where they get installed?