I'm attempting to be brief, so please let me know what additional information I can provide... 1995 F355 spider (2.7), 3 pedal car, Tubi Exhaust, Hyperflo Cats, 38K miles Here's the issue: A couple months ago i was cruising up the highway on a cold day. About 30+ miles at 65 - 80+ mph. Everything seemed to be running smooth until I got off my exit, stopped at a red light for a minute...Light turns green, upon acceleration my exhaust tone had completely changed. It was all of a sudden much deeper with a resonating 'flutter' type sound. I can also hear a ticking and/or misfire which appears to be coming from bank 1-4. - No CELs or SDLs. Didn't notice any loss in power, although I wasn't pushing it either. - Used the CEL flash to pull the codes; the only one I had was for the phase sensor - replaced phase sensor (noticed the old one had oil on it) - checked all wires for spark -- good to go - replaced 4 plugs on RH bank - found loose exhaust where Cat flows into the tubi. It was also loose at the Y-pipe, so I tightened both. - RH bank - noticed a white residue on the underside of Cat where the Cat flows into the Tubi, as well as the same white residue around where the o2 sensor is -- noting but black/gray in the tailpipe -- any ideas? - changed oil (added some Marvel Mystery Oil to see if the ticking may have been a sticky lifter) - put everything back together, turned the battery back on - cranked the car and let idle until fans came on (ECU relearn process) - idles right at 1000 RPM and is pretty rough (was never super smooth being a 2.7 anyway). - went for a light drive and no changes... - have a buddy coming over tomorrow and we're going to run a compression test on all cylinders. I did have a something similar happen last year after service. The exhaust had that deep flutter sound, but ended up going away after a few on/off drive cycles. I figured the issue then was that I forgot to perform the proper ECU relearn after the battery had been disco'd... Trying to diagnose, so I can fix the issue without blindly throwing money at parts...Any help, guidance, similar experiences would be greatly appreciated!
Check headers. Have they ever been replaced? When my headers went, the first thing I noticed was an exhaust sound change.
thanks, Bob...i was thinking this might be the case. I replaced the manifold previously, but only with another OEM. If I can find that they are bad/cracked, then Fab Speed is definitely on the menu...
It's a dead give away. Lower RPMs due to exhaust spewing out the side of the block, sounds like missfires..I had this happen on a 1972 BMW CS with a double gasket on the header..some peoples kids... It was awesome.. (sarcasm).
Header(s) cracked. Mine did the same & spontaneously resolved before ultimately blowing out and sending insulation fibers all over the engine bay. The spontaneous resolution has to do with heat swelling the cracks closed I was told.
Smoke test headers. Any shop with a decent smoke tester should be able to do. Do the intake too while you're at it for *****s and giggles. I borrowed a friend's smoke tester and did it myself. Never done anything like it before. Easy. My exhaust was intact but I found some pretty large intake leaks I proceeded to seal up. Good luck.
That's awesome. I never heard of someone doing it on the intake side. Makes a lot of sense. Everyday!
the issue resolving itself previously is what had me a bit puzzled. I drove the car for another 7 months or so without any further issue until recently. Plus, i don't have any sign of insulation fibers in my engine bay... regardless, as suggested, a smoke test is in order! Going to get some compression numbers today.
i agree! was thinking about purchasing a smoker, but those dang things are expensive considering how often it would be used. going to call around to some local spots to see if someone will allow me to borrow one for the day. Would rather not drive my car until I get it sorted
Did I miss the part about stock headers ? I did catch the Hyper Flow cats and Tubi exhaust. Maybe time for some Fabspeed headers.
yep! still running stock headers. I was hoping to wait till the end of the year for an engine out and throw on a set of Fabspeed headers at that time. Looks like that may be happening sooner than later once I can confirm the headers are the issue...
well, turns out we didn't have the right fitting for the compression meter. Tried a number of local places with no luck...going to have to do the compression test another day. However, i pulled the new plugs and found that the tip of #2 was black. It was clean everywhere but the tip. Looked like carbon build up. All other plugs look good. Put all plugs/wires back, started her up, pulled the #2 injector connector with engine running. There was no change with the injector pulled and/or connected... My questions are: 1. What would the symptoms of a "dead injector" be? 2. Please correct me if i'm wrong, but since the #2 spark plug tip is black, I'm assuming that there is fuel reaching the plug. I don't think that the #2 injector isn't clogged, but 'stuck open' -- is that even a possibility? 3. shouldn't i be throwing a CEL? Thanks!!!
can anyone advise with regard to my #2 injector? thinking about ordering one from RockAuto (i.e. GM Manufacturing). However, I believe the spray pattern might differ slightly. Any objections to having one injector that is different than the remaining 7 OEM? Thanks!
Run a compression test. You need to get a Snap On motorcycle compression test dongle with 10mm threads. If the cylinder is all dead, you should be throwing a CEL for misfiring (OBD2). A dead injector could be stuck open, in that case you will still fire but very rich. The excess fuel goes into the cat, burns red hot there. It may throw a SDL.
yep! need to get that compression test done. my car is an OBD1. no CEL and/or SDL thrown, but the car is definitely running rich.
Make sure your sdl has a bulb. I see you used cel to diagnose so we know its working. I believe i have had a sdl without a cel before.
Best of luck with your situation. If anyone needs a set of our headers or has any questions, I'll do my best to help you out. Our fabrication shop just completed a few sets the other day. Image Unavailable, Please Login
all bulbs are good. At least both CELs and SDLs light up when turning the ignition to the 'On' position.
those headers look beautiful! Definitely have me tempted to bite the bullet. However, I haven't been able to determine that my headers are the issue just yet. No cracks or blown insulation anywhere in the engine bay... Regardless, a set of Fabspeed headers is definitely on the top of my list!
