exhaust/fuel injection???

[*HEAVY-CHEVY*]

I recently had to replace my cats. I talked to multiple exhaust shops and they all told me that I cannot cut out the cats and weld in 2 new ones or it would throw the same code within a few months and also cannot install anything other than shorty headers as far as aftermarket. So I ended up spending $600 that I didn't have to replace my pipes from the manifolds back to the muffler. Then within a month I have the same code coming up. I believe it is p0420 for egr. After having it closely monitored on a computer for fuel pressure and such they tell me something is wrong with my fuel injection and I am only getting single digits on one side and double what I should in the other! My 97 Tahoe with almost 160K runs better than any other one I have ever driven! So a couple questions:

1. Anyone had any issues installing high flow cats?
2. Anyone encountering problems with fuel injection? (example. lines clogging and cracking)
3. Do I need any special tuning after installing both long tube headers and highflow cats?

 

[TigerEyz3]

The EGR code shouldn't have anything to do with replacing your cats... if your cats need replacing, replace 'em. EGR connects well before you get to the cats. I've read good things about the Magnaflow cats and have read from many that Thunderbolt cats are decent (not as good as the Magnaflows, but decent nonetheless and much cheaper). If you're looking for top-of-the-line, consider Random Technology - they're pricey, but worth it from what what I've read.

As far as the fuel injection situation, I've replaced my fuel spider and have read of many others doing the same because of injectors clogging (especially those using Cali fuel additives). I didn't have any problems with my original spider, but figured since I was already gonna be in the intake (gasket replacement), might as well do a few other things in the area at the same time (VMax spacer being the other thing).

Your rig will benefit from a good tune to take advantage of the LTs, but you've got high-flows from the factory so you wouldn't likely see any difference there.

 

[hapyspaz]

+1 on the EGR code having nothing to do with your cats.

The spider injectors, while they do their job, are not optimal. The issue you are having with inconsistent fuel pressure readings on both sides is based on the fuel pressure regulator though. Unfortunately, it costs the same amount of labor to replace that as is does the injector setup itself, just more $$ for parts to do the whole kit.

I installed high flow cats (I beleive it was cherry bomb brand), I got a kit that had the pipes from the manifold, the cats, and the pipes to the muffler, all stainless steel. I wanna say it cost me $300 for the setup. My Tahoe was throwing O2 codes left and right before replacement, but my O2's were fine and we noticed that one of the cats was discolored. Ever since replacement, no O2 issues.

I have never heard someone say they can't use a certain header. That sounds to me like a lazy exhaust shop that doesnt want to fab pipes to connect to shorty headers. The only engine I know of in OBS that headers had to be super specific on is the 454SS.

No tuning would be required, but it would be recommended to get a BB tune so as to maximize the changes you make.

 

[fyremanpat]

some how my last posts were deleted.. but p0420 code is Catalyst System Efficiency Below Threshold (Bank 1)...try cleaning your MAF..I had this same problem. New hi flow cats and 4 o2 sensors and still had the problem.

 

[*HEAVY-CHEVY*]

p0420 code is Catalyst System Efficiency............

This is a very broad range of issues that can be going on and the more you read in it CAN be egr as well as mean catalyst replacement. Everybody's input is appreciated and helps! How much does the spider injector setup cost (for parts) and did the vmax spacer give you any performance perks?

 

[fyremanpat]

i really doubt its ur injectors..injectors are anywhere from 300-400 though

 

[hapyspaz]

p0420 code is Catalyst System Efficiency............

This is a very broad range of issues that can be going on and the more you read in it CAN be egr as well as mean catalyst replacement. Everybody's input is appreciated and helps! How much does the spider injector setup cost (for parts) and did the vmax spacer give you any performance perks?

Okay, so it IS a Catalyst System Efficeiency code...

Find someone you trust, have them read your O2 sensors pre and post cat to make sure they are functioning properly.

With the engine running, tap on the mass air flow, if the engine stumbles or changes idle, clean or replace mass air flow.

Ask any exhaust shop, and they will always tell you to do a tune up right before, or right after replacing cats.

New plugs, wires if needed, cap, rotor, fuel filter, maybe even a PCV.

Theu fuel injectors are generally going to throw a misfire code when they are acting up. Only reason we were leaning towards the injectors was your input about the fuel pressure readings being bad.

 

[*HEAVY-CHEVY*]

Well I cleaned the maf sensor and cleared the code. My check engine light hasn't come back on yet (about 4 days) we'll see if it stays off. Will this sensor being dirty cause any problems other than the code being thrown? Such as power loss or poor gas mileage? I've only been getting about 14 when I used to get about 16 to 18 before I had any of these issues.

 

[fyremanpat]

yep! its crazy how the little things cause such a big affect

 

[nimrodcs]

I'd replace all four of your 02 sensors if you haven't already. I had the same code, replaced all four of mine. No more code for 4 months now.