Rev limiter
 

What govern's the rev limiter, ECU?
I cant rev past 5000. PR4 (integra LS) ECU on a JDM D15b non vtec, CRX HF.

Re:Rev limiter
 

yuppers

Re:Rev limiter
 

yuppers?

Do you have a CEL?

Sounds to me like you're in LIMP MODE.

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yeah, that would be my guess^^^^

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Nope, no cell whats limp mode?

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limp mode is how your ecu runs if you have a cel, check to see if you have any codes anyways, sometimes you can be throwing codes without the cel coming on. if there is a problem, the ecu will run in "limp" (safe) mode so as not to harm the engine, usually it will idle kind of high and run rich along with not being able to rev over 5k

Re:Rev limiter
 

What a coincidence, my idle is ------- crazy. When I start her up she idles at about 1500 and slowly climbs all the way up to 2000, I need to get that ---- fixed, I probably need a new EACV. whats crazy is that in nuetral, if I give it some gas she'll rev all the way to 5000 from 2000, but in gear she drops to about 1500 and then goes up WTF? after a while she'll idle at about 1000 and a little over, and sometimes I see it as low as 300. I have noticed a CEL, but only for a couple of seconds, then it turns off. I figuered that the road bumps cause my lights jiggle on and off. I also have a hand brake light that wont ------- turn off. I dont know, what do you guys think?

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CEL or not, you're in limp mode buddy. Limp hard idles the car @ 1500 rpm (full IACV duty cycle) and rev limit = 5000.

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How the Hell do you get out of limp mode?

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check the codes.. can't hurt, then reset ecu.

Reset ecu: In the engine fuse box pull the fuse labelled hazard to 15-20 sec. Re-insert fuse, and voila! ecu is reset.

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right, just check your codes, and fix whatever it tells you is the problem, then reset the ecu. do you know how to check your engine codes to see what cel it is throwing??

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Yeah, I know ho to check for engine codes, got the list and everything.

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well do that and tell us what you get.......

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for those of us that dont how do you chek?

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holy ----, it's been posted a million times :P, look in the tech section under any topic that has to do with "CEL", all you do is use a jumper wire (paper clip), to jump the 2 prong "service wire" behind the passenger side kick panel, then you turn you ignition "on" and read the codes, this is a brief "how to", but you can find step by step detailed instructions in the tech section.......

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most likley its because you have the HF engine, and those fuckers are 8 vavle pos's, so its not reving high because of its inafficiency (i can spell) i had an 88 hf with a a6 ecu. bwhahahahahah peice of should wouldnt rev over 5800

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he doesnt have the hf engine

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Yeah what he said, I have a JDM D15b 16 valve.

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is your pr4 obd1 or 0, if it's 0 (for those who don't know) a light inside will flash the number of the problem code, very simple.

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Try swapping the distributor.. more than likly the problem. Your Crank positon sensor is in their, and if it isnt reading right, you will get a low rev limit. The Cylinder sensor looses its output to the ECU, and it just cuts out. I've never heard of limp mode on a OBD0/1 car not letting you rev past a certain amount.

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I know ---- all about obd0, but I promise you limp mode on OBD1 only allows 5000 rpm, idles @ 1500 and generally runs like total ----.

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Hmm, explain what code or what type of situation you would be in to get into "limp mode" and get this "low rev limit" I'd like to reproduce it. If you get a Map or TPS cel you will still be able to rev over 5k, same with a IACV code. The car will run like complete ass and stumble, but should be able to rev.

Re:Rev limiter
 

knock sensor, checksum invalid (or not disabled) on a rom, code 13 (PA sensor), injector test and a few other things that arent on the top of my head. the ecu has a backup microcontroller which is what takes over in the event of a limphome situation. at that point it is NO LONGER running off the main MCU... therefor its not using the main MCU's program if its internal rom or the external rom.


I agree, and I now don't think this is his problem after saying he didnt have a solid CEL on the dash (assuming this is a OBDI car). Maybe he has his distributor at full advance... I did that once accidentally and got results like hes reporting :) Or maybe its got sensor problems like you also suggested.

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i got the solid cel on broke the second sensor while putting the kit on 2 years ago. too lazy to fix and normally to drunk to care. fucker still revs and pulls like a beotch no limp dick here

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You guys arent hearing me, solid CEL doesnt mean limp... it just means trouble. If you wanna experience limp and have a socketed ecu, pull the ROM and then run the car. Then you'll know limp :)

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OK, here is my $0.02 on this thread (which, by the way, is getting way out of control):

Facts:
Limp mode OBD0 will have these characteristics, solid CEL (doesn't mean solid CEL = limp mode, but limp mode will haev a solid CEL), 3333 rev limit (based the code from the DASM), rough revving, between 1000 and 1500rpm idle.

Your problem: Cam timing is off. Check it, I bet your belt slipped.

CYP sensor will not cause improper rev limit, will however, cause misifing/detonation.

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Okay no CEL codes, I reset the ECU (ODBO) and got the same results. I then hooked up to a PM6 and was limited to 6000, went back to PR4, still at 5000. No CEL codes on either.

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Cam Timing.

I'm positive that is your problem, check it. Tell me I'm wrong. ::) You're probably a tooth, or a tooth and a half off.

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Ahh mannn.....I dont have a timing gun >:(

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if the contact points inside of the distributor (pick ups) are out of range you can easily get codes 4/8 Crank/TDC sensor. This can cause a low rev limit, I've replaced dozens of faulty Distributors throught the years on hondas.

Cam timing is not going to lower your rev limit, you can be 2 teeth off and it will still rev, just rev (slow) or (fast) depending on which way it slipped. If the belt slipped any more than that it would bend valves.

The way he has described his problem it sounds like a Fuel/Spark cut is happening at 5000 rpms.

Just a suggestion, try a known good distributor, toss it in and see if it works. If not... try something else.

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I have ran my car with the cam timing off at least two teeth and it still idled and reved to the normal rev limit. It ran like ----, but it still ran the normal rev range.

Nobody has asked this yet, but are you boosting this motor? Have you check the o2 sesor, fuel filters, all that ----?
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Re:Rev limiter
 

Tooth and a half- that'd probably be tough to do, maybe with an adjustable cam gear, but slipping a belt...?

;) you know we love man, I'm actually thinking that may be the problem, see it happen before. And you don't need a timing light to check if the belt slipped, just put the crank pulley at TDC and check the cam gear... not too hard...

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I'll check my belt tomarrow.

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When I put a F22B1 VTEC head on my F22A1 I accidentally had the cam off by 2 teeth. I forget if it was advanced/retarded now. It revved to redline and idled fine but i experienced the following:

1.) I had to put my distributor at full advance/retard (I forget now.. this was a year ago) to get the timing light to show 15BTDC on the fly wheel marks.

2.) It had no balls... I musta killed 40hp having the cam timing off.

every car/situation is different though!

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Check the coil output. I had a Mazda MX6 once with a weak coil that wouldn't rev past 4000 RPM. The spark was very weak, it would only jump about 1/8" and was yellow, not bright blue. I have seen lots of bad coils on Hondas over the years. But they usually wont run at all. Just a thought.

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i bet it's your coil or ignition module in the distributor.
I did the mpfi swap and my ignition module was fucked up, I couldn't rev passed 4000 and everyone said it was in limp mode, it wasn't the ignition system was taking a dump and couldn't handle the higher revs. Goto autozone and swap them out in the parking lot, if it doesn't work just return them. :)

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What about the variable rev limits achived when switching from PR4 to PM6, PR4=5000 PM6=6000. Is this acceptable with what you are suggesting? I'm at work right now so I wont be able to check my timing belt for some time.

-not boosted for future refrence-

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Cam timing is NOT, going to lower your rev limit, especially to 5000 rpms. "tooth and a half" wtf is that? your either 1 tooth off, or 2, not a half? ::)

Faulty Coils and ignitors can do the exact same thing as mentioned above without throwing a code. Thats why I said try swapping in a different Distributor, and if that doesnt fix it, try swapping in a different ECU.

Its pretty distinct if the car is off 1 tooth Adv/retard. But it never hurts to check timing.

Jeff