Wait... is it possible all my problems are exhaust related?

"Akio Ohtori - RIP Oppo" (akioohtori) 03/25/2019 at 13:51 • Filed to: project golf ball

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It isn’t the exhaust. There is no way it could be the exhaust. Except maybe it is the exhaust? Let’s think about that for a second...

Quick summary for the uninitiated: For almost as long as it has been on the road in my care, my 1986 Honda Civic wagon has had problems with sustained high throttle. It starts to lose power and backfire though the intake. I’ve done a lot to diagnose and solve this problem, but haven’t. It did go away for a while, but now it is back.

Alright, so I had some shower thoughts on this while trying to figure out what the problem is/ was. When troubleshooting earlier I’d noticed the muffler had a small hole in the front of it. Annoying, as it was brand new.

In fact, all of these problems started immediately after picking it up from the exhaust shop.....

Ok, I don’t actually think the exhaust is the problem. I hadn’t really driven the car much or hard before dropping it off to get the exhaust put on. But that said the problem presented immediately after picking it up. As in within a mile away when I was getting on an on-ramp. Now with the muffler failing in under 300 miles... is it possible that is my problem? I’ve also noticed a TON of water coming out of the exhaust, which is allegedly a sign of a bad exhaust? Also a bad HG... so there is that.

What does oppo think? Did the muffler man sell me some bad pipes?

Highlander-Datsuns are Forever > Akio Ohtori - RIP Oppo 03/25/2019 at 13:59

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These problems do manifest with a partially blocked exhaust . I know, I had a cat explode and plug my exhaust and the truck ran fine to 30 mph then just died on it’s face. It started fine too. 

farscythe - makin da cawfee! > Akio Ohtori - RIP Oppo 03/25/2019 at 14:02

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didnt the muffler man want to buy it from you?

i call sabotage

sabotage!!

Chariotoflove > Akio Ohtori - RIP Oppo 03/25/2019 at 14:03

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I don’t know squat about Honda in specific or exhaust systems in general. I do know about troubleshooting and following clues. Don’t saddle yourself with assumptions that rule out “impossibilities”. Keep an open mind. Maybe it is the exhaust. So then think w hat’s the cheapest and easiest way to test that theory.

Akio Ohtori - RIP Oppo > Chariotoflove 03/25/2019 at 14:25

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Yeah I’ll either run it by (the muffler needs to be replaced anyway) or disconnect it entirely.

Akio Ohtori - RIP Oppo > farscythe - makin da cawfee! 03/25/2019 at 14:25

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Well remembered and yes that was 100% my initial thought at the time haha.  But nah he is a good guy... probably.

Tekamul > Akio Ohtori - RIP Oppo 03/25/2019 at 14:30

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Simple remedy : pull the exhaust off behind the header. No blockage! Note : you may want earplugs

Manwich - now Keto-Friendly > Akio Ohtori - RIP Oppo 03/25/2019 at 14:30

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Hmmm... maybe.

When I had my Wagovan, I installed a custom 2" or 2.5" exhaust from the cat back... and it did provide a noticeable power improvement over 5000rpm.

Akio Ohtori - RIP Oppo > Tekamul 03/25/2019 at 14:31

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That is the plan.  I don’t think it’ll be that loud.  When I bought the car, it had no exhaust after the cat and honestly wasn’t much louder than a normal car.

random001 > farscythe - makin da cawfee! 03/25/2019 at 14:34

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Yes

StudyStudyStudy > Akio Ohtori - RIP Oppo 03/25/2019 at 14:38

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Does it have an ECU? If it is post o2 sensor that doesn’t make a whole lot of sense. Assuming fueling isn’t an issue and you don’t have any vacuum leaks that really only leaves timing and spark plugs. Keep in mind that is a big assumption that fueling and leaks aren’t a problem. Have you checked timing?

Funktheduck > Akio Ohtori - RIP Oppo 03/25/2019 at 14:42

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You’d be surprised. My friend drove his B18/16 (don’t remember) after a swap, briefly,  with just headers and it was real loud. I know not the same engine but still a small-ish 4. 

MM54 > Akio Ohtori - RIP Oppo 03/25/2019 at 14:49

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Does it have cats? They may be clogging, though it seems unlikely it would match your problems it’s worth checking out. I don’t see how a bad exhaust would lead to dragging your air hose in the wet primer. (I had a moth land in fresh paint once so I can joke about these things now)

Akio Ohtori - RIP Oppo > StudyStudyStudy 03/25/2019 at 14:50

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Sorry, should have included related articles . No ECU. No vacuum leaks, fuel delivery well within spec (basically perfect) , new fuel pump, lines, filter, spark plugs, wires, cap, rotor, coil, carb, etc . Running out of options, tbh haha.

Akio Ohtori - RIP Oppo > MM54 03/25/2019 at 14:55

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What is even more fun is I can’t test this theory until I finish the dip!  Door handles are taped shut!

Akio Ohtori - RIP Oppo > farscythe - makin da cawfee! 03/25/2019 at 15:01

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Also apparently you suggested this at the time . Or sort of anyway...

farscythe - makin da cawfee! > Akio Ohtori - RIP Oppo 03/25/2019 at 15:03

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welp im nothing if not consistent :p

AuthiCooper1300 > Akio Ohtori - RIP Oppo 03/25/2019 at 15:06

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Car had been stood up for a while, right? Well... did you c l e a n your fuel tank ? Ideally it should be steam-cleaned , o f c o u r s e .

I wonder if there is a “crudberg” somewhere. Big enough to obstruct the flow of fuel w h e n y o u a r e a c c e l e r a t i n g but not small enough to be sucked through the fuel line.

After having the bodywork of car restored I started experiencing strange problems with f u e l d e l i v e r y t o t h e engine. Trouble is, the whole thing w a s , f o r s u r e , in perfect condition: newly rebuilt engine, new fuel lines, rebuilt carb, etc.

It turns out there was a paper towel inside the fuel tank. We imagine that when they were restoring and painting the tank they put a ball of paper towels in the opening so that no dust went in. And one of them stayed inside.

As I said before, big enough to block the fuel outlet from time to time but not small enough to properly lodge itself there.

davesaddiction @ opposite-lock.com > Akio Ohtori - RIP Oppo 03/25/2019 at 15:22

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ALL your problems...?

Akio Ohtori - RIP Oppo > AuthiCooper1300 03/25/2019 at 15:25

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T hat is a terrifying cautionary tale.  I drained the tank and the gas that was in it looked OK, so I gave the fuel system a clean bill of health based on that alone.  You never know though!

AuthiCooper1300 > Akio Ohtori - RIP Oppo 03/25/2019 at 15:38

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Also... back in the day when cars had fuel tanks that vented directly to the atmosphere you would get a puzzling behaviour from your engine if the v ent itself got blocked for some reason.

Yours is a newer beast but what if the blockage is in the return fuel line to the tank? Did you check that one too?

StudyStudyStudy > Akio Ohtori - RIP Oppo 03/25/2019 at 15:46

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Hmm, have you checked timing both with a light and mechanically? If the base is set, I’ve seen similar issues with a bad dizzy or loose/cracked vacuum advance line . The vacuum advance can’t maintain the advance when it is sustained. If it is carbeurated, I had a similar issue with a faulty connection on the fuel electrics. Basically as I accelerated a wire would come away from the fuel relay, so the car would run on the fuel in the bowl, as soon as I let off the throttle it would fill again, so it would only be a problem when I was under sustained load.

Akio Ohtori - RIP Oppo > AuthiCooper1300 03/25/2019 at 15:46

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Good thoughts, but sadly I checked both! I’ve heard of clogged vents causing weird problems, so I pulled my gas cap and made sure the problem persisted (it did). When testing fuel pressure and flow, I checked it with the return connected (3 psi output) and capped (4 psi output) so I assume the return is good? That said if I disconnect the return after the 1-way valve, fuel will spray out of the return... which seems odd.  Might be worth investigating!

AuthiCooper1300 > Akio Ohtori - RIP Oppo 03/25/2019 at 15:54

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The fuel tank in my F i a t Uno (carb engine) always seems to have a certain amount of positive pressure so maybe it is not that significant. B u t w ho knows.

O n t h e o t h e r h a n d y o u r s u g g e s t i o n o f a n e x h a u s t b l o c k a g e s o u n d s p r e t t y i n t e r e s t i n g . B u t i t s o unds a s i f a t t i m e s t h e o b s t r u c t i o n i s n e a r l y c omplete. W o u l d t h a t b e p o s s i b l e ?

CobraJoe > Akio Ohtori - RIP Oppo 03/25/2019 at 15:58

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We had a truck that had problems with the tune and it kept blowing out EGR gaskets, and we didn’t even consider that the exhaust could be the problem, it had a glasspack on it.

Turns out, it was a “ turbo style” glasspack with undersized internal tubing and a convoluted path that choked itself with carbon. Replaced that stupid muffler with a proper glasspack, and it fixed everything.

So yeah, exhaust blockage can cause issues that are hard to troubleshoot. 

LOREM IPSUM > Akio Ohtori - RIP Oppo 03/25/2019 at 16:05

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It is possible that the cat has  started to break up and there is a piece of debris somewhere, too large to make it’s way downstream, creating a restriction only noticed when under a heavier load.

Couple ways to check.

If that Civic was like mine and only had the one cat just after the header, it was easy to unbolt the cat and remove it. So do that and take it for a rip on an open header. If problem solved, exhaust is blocked somewhere.

I you can’t yank the cat, remove the primary o2 sensor and take it for a rip with the sensor removed and the bunghole open to atmosphere. Again, problem solved, it’s a blockage.

(Think it’ll still run off the alpha-n tune even without the primary o2 connected. Ymmv)

Edit: Should have read the thread. No ecu, so forget all that o2 sensor jazz I was talking about.

ITA97, now with more Jag @ opposite-lock.com > Akio Ohtori - RIP Oppo 03/25/2019 at 16:26

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You may be surprised. Catalytic converters are very effective at dampening sound. The first couple of races the racecar ran with the OEM exhaust minus the muffler being cut off. It was still the quietest car in the run group. Once I did up the exhaust system via a port matched, ceramic coated header (gusseted and flex pipe added at the collector) and 2.5" mand re l tubing back to a simple F lowmaster 40 series it is much louder. As in could never been driven on the street above idle loud.

twodudesnape > Akio Ohtori - RIP Oppo 03/25/2019 at 17:05

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Regarding your HG comment at the end...I’ve heard these EW1 engines like to blow the HG between the 2 and 3 cylinders. Mine was pretty burnt out there when I took it apart. Don’t think it’ll cause any issues besides low compression in those cylinders and almost certainly not related to any of these other problems you are having.

Akio Ohtori - RIP Oppo > twodudesnape 03/25/2019 at 17:12

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Good to know!  Thanks!

razorbeamteam > Akio Ohtori - RIP Oppo 03/26/2019 at 11:35

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I’m gonna echo some others here and suggest a cat delete. I think that if you were having mixture issues you could have been clogging the cat with fuel or maybe coolant, oil, etc. 30 year old cats are probably not the most high flowing things. It would explain why you’re only having the issue at high RPMs. I say hack that thing out and see if you get the same issue. 

Akio Ohtori - RIP Oppo > razorbeamteam 03/26/2019 at 11:41

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Sorry I didn’t refute the cat thing. It did have a cat... but since I didn’t expressly tell the exhaust shop to keep or replace it, I no longer have a cat. Also, weirdly, my problems don’t seem to be at high rpm, just sustained high throttle.  The temporal component is what makes this so effing weird.  Well... it is what makes it seem like a fuel problem but it apparently isn’t.

razorbeamteam > Akio Ohtori - RIP Oppo 03/26/2019 at 11:53

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Hmm, that’ s a head scratcher . The hole in the muffler could be pressure related? Maybe there’ s a blockage elsewhere in the system or a gasket that was installed wrong.

I had an issue once that I was sure was fuel related and went through hell cleaning all the lines and injectors, etc. It ended up being some loose ignition wiring that was causing intermittent stumbling. Doesn’t sound like what you have but my point is that the answer may be something you’ve already checked or replaced. 

Akio Ohtori - RIP Oppo > razorbeamteam 03/26/2019 at 12:01

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Yeah my best lead (pun unintended) is that is seems like I can make it run better/ worse by playing with the wires coming out of the igniter .  That is the next project when the car isn’t taped shut.