Can't Rev past 3000 RPM - CEL No Code? High speed miss 1991

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Hodag
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Can't Rev past 3000 RPM - CEL No Code? High speed miss 1991

Post by Hodag » Wed Sep 23, 2015 12:09 pm

OK here's the situation. Basically can't rev past 3000 in any gear. That's where the engine used to get a little kick of power and start winding up. Now it backfires or lurches.

If I Rev up in neutral (it's a stick by the way) at exactly 3000 high speed miss.

Starts and runs, kind of weak power. Fuel mileage went down from 28 to about 20 at the same time.

Did the usual, plugs and wires. No change.

I jumped the little blue plug under the passenger side, and get no codes. I'm assuming I'm doing something wrong with that?

I fear that it's timing at 293,000 a stuck valve, bad rod, or if I'm lucky fuel filter or maybe injector? I mean, there have been a number of people, smarter than me, who came up with different guesses. No CEL code to help. Last one said, probably the coil. Hey that would be nice. Just replaced the ignitor for the 4th time a few months back.

So bottom line two questions:

What happens at 3000 RPM? That's where the motor started putting out more power?

How do I read the CEL code on this thing?

1991 Accord EX wagon - 5 speed, everything stock original motor.

ps needs the seals on the spark plug tubes replaced, but has new wires, plugs and they are currently dry. If I do it myself, is this something where I can replace the seals and gasket without adjusting the valves or anything more than time and being careful?

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by John » Fri Sep 25, 2015 9:37 pm

Nothing really happens at 3000 rpm.

The pistons are moving faster and there is less time for the fuel to burn in the cylinder. Might have something to do with it.

Have you done a compression test? Or better yet, a leakdown test? Maybe you have a blown head gasket or the rings are worn out.
1997 Accord EX 5-speed wagon (auto to 5-speed swap)

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by Ben » Mon Sep 28, 2015 9:45 pm

Could a clogged/broken catalytic converter cause this?
Golden Era Garage: 94 Accord EX wagon 5 speed/ 97 Integra LS hatch 5 speed

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by John » Mon Sep 28, 2015 10:04 pm

In the old days catalysts could clog. But modern catalyst design is a lot better and it is very rare for the ceramic substrates used today to clog. Possible, but not likely.
1997 Accord EX 5-speed wagon (auto to 5-speed swap)

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by blacksheep » Mon Sep 28, 2015 11:04 pm

I had something like that happen after washing my engine bay once. Water had seeped into one of the connectors of the engine wiring harness.

Unplugged the connector, water poured out. I packed it with dielectric grease, plugged it back in and it's never acted up again
I did it all for the nookie

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by Ben » Sun Oct 04, 2015 3:51 pm

I had my catalytic converter clog in my ULEV VTEC 2000 Accord. It wouldn't rev very high when driving and could barely make it up hills. I do not remember if it would rev higher in neutral, but it seems like it wouldn't. I know this cat was probably a lot more restrictive than what you have though.
Golden Era Garage: 94 Accord EX wagon 5 speed/ 97 Integra LS hatch 5 speed

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by Hodag » Thu Oct 22, 2015 6:56 pm

Update, just so it's not a question without anything else.

Took it to a shop that has the computers to check. State Emissions place, so he see's loads of cars.

Says, he can't read the code and neither can I, because the computer got wet. I don't know why the car even runs. So he found a used computer so he could at least read the codes, and that computer is bad.

So far, he says the EGR (not the sensor) ports are plugged. Hmm at only 294,000 miles? ;)

Meanwhile this will be an update. I need a computer. Anyone know where I can get one for a 1991 EX, Wagon, Stick... mechanic says, they are not interchangeable from automatics and sedans and wagons. He says they list a different number for an EX!

What happens if I put the wrong computer in? Like an automatic version for a sedan?

I'll post in parts wanted - 37820 PT6 A10 computer needed.

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by John » Thu Oct 22, 2015 8:15 pm

ECUs are interchangeable between sedans and wagons. No differences of any kind. Fortunately for you, because there aren't many wagons with manual transmissions.

ECUs are not interchangeable between manual and automatic. I'm not sure your car would even run with an automatic ECU, as it is looking for a number of inputs that manuals don't have.

I'll bet an ECU from a 1990-91 LX would work fine. Only difference between the LX and EX engines for 1990-91 was that the EX had a better header, for an extra 5 hp. This really isn't enough for an ECU to even notice. So, any ECU for a 1990-91 Accord sedan or wagon, LX or EX should work fine, as long as it's for a manual transmission.

In fact, an ECU from a 1992-93 Accord LX manual (sedan or wagon) should also work fine, as there weren't any differences between the LX engines from 1990 to 1993. However, an ECU from a 1992-93 EX will not work properly, as it had a different camshaft and a dual-runner intake manifold.
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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by John » Thu Oct 22, 2015 8:18 pm

But this does explain why you couldn't rev past 3000 rpm. ECUs have a "limp home" mode, so that the vehicle won't strand you even if the ECU isn't getting a critical sensor input (such as MAP sensor or throttle position). It seems pretty clear that the water fried the main circuits, but the limp home circuits were still operational.
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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by Hodag » Thu Nov 12, 2015 7:11 am

John wrote:But this does explain why you couldn't rev past 3000 rpm. ECUs have a "limp home" mode, so that the vehicle won't strand you even if the ECU isn't getting a critical sensor input (such as MAP sensor or throttle position). It seems pretty clear that the water fried the main circuits, but the limp home circuits were still operational.

Sounds like you pretty much nailed it.

What I learned, A11 is CA computer, A10 is the rest. According to junkyard (and you I believe?) Any PT6 will run the car, but I understand from others, some functions may not work properly.

After pulling the "wet" computer, and replacing it with a faulty one that someone shipped out, (blew fuses) First computer back in... the car changed to running at 1500 RPM all the time, instead of idling at 1000 RPM. Still started and ran up to 3000 where it would just miss like all getout. I also heard a clicking sound, which is gone with the newest computer. I guess that's where it was coming from?

The update is, used computer from eBay, A10, plugged it in, the car runs the best it has in years. I also had that random "won't start - wait 30 seconds, runs fine for weeks", problem as described in another post and I'll be waiting to see if it's gone.

I wasn't sure if this 1991 had a limp mode, but that describes it perfectly. I would also note that the RPMs drop to nothing, very fast when shifting in limp mode, unlike normal operation where they gradually decrease.

Next question, where's the water coming from? I think it's the side weather stripping on the passenger side doors. I can't see wet when it rains, no dripping? Floor in rear was getting a puddle, smells bad. Now has drain holes. =D> And that happens when the car is parked and it rains!

295,000 miles and counting.

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by John » Thu Nov 12, 2015 9:12 pm

Glad to hear the car is running good again. I hope you can track down the water leak.
1997 Accord EX 5-speed wagon (auto to 5-speed swap)

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by Ben » Fri Nov 13, 2015 6:56 pm

Do you have a sunroof? My 88 prelude had tubes running from the sunroof, through the trunk out the bottom of the car. Those would become clogged and leak in the trunk. I located the tubes and used an air compressor to blow pine needles and junk out. Not sure where the wagon tubes would run to, though.
Golden Era Garage: 94 Accord EX wagon 5 speed/ 97 Integra LS hatch 5 speed

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by Hodag » Mon Feb 15, 2016 12:12 pm

Just to update. Car runs the best it has in years. First off the fuel pump was going bad and would shut down at random. Wait 5 minutes, run for a month. Turn a corner - dead. Park and wait. :-? The last time I was on a cold engine, full tank (which is when it was it's worst) going up a steep hill. That's when I gave up and had the work done. Tired of the hit and miss with running at random.

Then the computer issue which could have been just age, or moisture? It was a dry day, Sunny, rode to work fine. Started to come home and "Check Engine" was on. That's when it was in limp mode.

I'll check for tubes in the Sun Roof, thanks. I get water in the tailgate from? Total mystery, what's to leak? It's solid, unless there are some weather seals on the lights. And when I say IN the tailgate, that's what it is. I open the back and it drains out the bottom holes.

Just saying, once again, the forum has good advise and information.

I still hope to find a replacement for the 1991, Accord Wagon, stick EX, some day. Texas car, because this one was Wisconsin and lasted ten years, going for 300,000 miles soon. Rust will be the killer, not mechanical.

Oh and ps I believe this is the original clutch.

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by Ben » Wed Feb 17, 2016 10:34 pm

The tubes run down the rear door panel I believe and drain into the trunk and out the bottom. If the bottom of the tube is clogged it leaks into the trunk area. Again, I haven't had this problem with my wagon but I have in other Hondas.
Golden Era Garage: 94 Accord EX wagon 5 speed/ 97 Integra LS hatch 5 speed

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Re: Can't Rev past 3000 RPM - CEL No Code? High speed miss 1

Post by John » Tue Feb 23, 2016 8:16 pm

Glad to hear it's running right. The engines (and manual transmissions) are amazing.
1997 Accord EX 5-speed wagon (auto to 5-speed swap)

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