Did my exhaust cause loss of power and sputter?

[1970mule]

So, i recently had an exhaust shop install a new exhaust, i had headers on before. SO, i a not certain but it feels like i have less power now on acceleration and also it sputters if i step on it and seems like it will die it is not all the tme i would say maybe 40% of the time. I have a 302 EFI out of a 93 mustang, it worked great for years only trouble was now. The shop said they made sure no exhaust leaks and i don't hear any, but it just overall does not feel right. i am thinking a few things. maybe i have a vacuum leak somewhere but i am pretty sure no, maybe high pressure fuel pump is starting to go. any suggestions

 

[Broncobowsher]

Exhaust can be odd. Even if everything is done right, there can be strange harmonics that match the engine just right to make it unhappy.
Or you could have other underlying issues that you just now notice. Or installing the exhaust disturbed something unrelated and that makes things unhappy now. A fuel line got shaken and that broke stuff loose that clogged the filter enough to now be an issue. A thunk against the gas tank knocked that last tiny bit of rust loose that chokes fuel flow.
It's quiet now, so it sounds slower.

The sputter I consider real. So I think you have an actual problem. As compared to feels slower with new exhaust as sound is part of the feel. A fart can on a Honda doesn't make it faster, but to the teen who put it on, it feels faster.

 

[1970mule]

Thanks for the response. Well as for the sound it is maybe a little louder than the ones i had before. i had flowmaster 40s on before now i have something else cant remember got it from Duff. BUt you maybe on to something on the fuel thing i will have to check that and i guess i need to check the injectors as well to see if any are clogged and change all filters. i appreciate the leads.

 

[m_m70]

02 sensors?? I run a carb so not really familiar with affects f they were changed up. Just thinking out loud..

 

[Brush Hog]

Did they replace headers/manifold? If so they might have removed plug wires and maybe even spark plugs. Check spark plugs and plug wires for a loose or misplaced wire or one touching manifold/header (melted or shorting out).

 

[Wild horse 75]

You may just need to drive it a bit so the computer can get use to the new exhaust. It may also be time for a tune up and the new exhaust has just magnified that fact. I spent many years working on 5.0L mustangs. I’ve done thousands of exhaust kits on them and they can all react differently.

 

[nvrstuk]

As already mentioned... O2 sensor.

How is O2 sensor mounted in the exhaust? How far from the collector?

Maybe they messed up a wire to the O2 sensor?

You had headers before but what now? Stock cast iron manifolds?

 

[73azbronco]

02 sensors?? I run a carb so not really familiar with affects f they were changed up. Just thinking out loud..

this^^^

 

[1970mule]

So I have new stainless headers, everything is about rhe same on the headers as far as O2 placement, maybe I will run codes and see if something is off. But I may have found something. I see a gas leak need to see where from but it's from a line I think a feed line nor return so maybe that is the problem where it is not building enough pressure. The stock efi 93 mustang fuel pressure should be around 40 correct, if low what will happen? Thx folks

 

[nvrstuk]

If you are leaking enough fuel to cause low psi at the regulator you will have a huge pool of gas under your car in 20 sec. Depending on the flow of the pump but at idle more than half the fuel getting pumped by the fuel pump, it's coming back in the return line or being dumped onto the ground in your case.

What I'm saying is, if you're losing so much fuel that your pressure is being reduced. You're losing a lot of fuel and the low fuel pressure cause is not from a leak.

On the fuel rail, there should be a schrader valve that you can hook a pressure gauge on and give us the fuel psi.

 

[1970mule]

Got it well the psi reads between 35 and 40. I will next look into the maf sensor. As I am getting stumped.

 

[nvrstuk]

I'm with ya as I'm running a terminator X and I am getting a lean reading on my AFR & digging into that...

 

[1970mule]

This is driving me nuts. I've changed nothing for the most part. I mean maybe when I hade to pull the engine I could have missed a vacuum line or something, but I have triple checked them and all is hooked up as it should. So the fuel regulator is good so no on that. The low and high pressure pumps are good. I checked the iac seems fine. The MAF seems to be ok I unhooked it and the engine stumbled. I have not checked timing but don't know how that could have changed. The mystery thickens.

 

[1970mule]

So, i think i figured it out, well at least the stuttering and decel popping. i had a vacuum leak. It was the hose from the drivers side valve cover that connects to the throttle body. seems like the problem is mostly gone but still sometimes i get a stumble and lack of power. but very inconsistent and very infrequent. Also my mpgs seem down. i mean i know its a bronco but i used to get 14-15 at best. now it seems its in the 8 range. any ideas? much appreciated.

 

[nvrstuk]

14-15 accurately figured mpg for a Bronco is about tops.

So 8 is an issue.

My O2 sensor died & it is still about 1/2 power although afr #'s are much better. Had one overnighted to Moab where I've been playing on rocks.

Looks like I need to study up on Term X as possibly getting stranded from a user fixable issue isn't acceptable.


After checking all other possibilities...check your O2 or get a new one.

The 4.9 lsu Bosch oxygen sensors are not nearly as robust as the ones i've been using for the ten years previous for Qtrhorse... almost went Dominator because of it but couldn't justify the extra thousand dollars... and I didn't need the other 44 inputs that a Dominator uses

 

[1970mule]

Yea i was thinking that also. i will look at codes on my next days off thank you

 

[ssray]

With all the talk on O2 sensors along with a new exhaust I'm wondering how much welding was done. Might be a possibility of sensor damage if it was left in. I've don't know about the O2's but you do need to be careful around electronics when welding.

Well AI mentions pulling the negative battery connection and the sensor so it could be an issue.