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Grizzly 700FI EPS, Intermittent Hard Start, EPS Light on, Codes 53 & 54


Sha35297

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So I have used the service manual to troubleshoot every sensor on this bike. Everything tests good accept the EPS Control unit. However, I do not see anything in the manual that suggests that this will cause the issue that I am having. The bike will start instantly when the button is pressed sometimes and then other times it wants to turn over forever and make a horrible knocking sound. Sometimes backfiring. After cycling the ignition it will sometimes start up right away. I have triple checked the timing and also the valve clearances. Everything checks out. The bike is for a customer that really doesn't know anything about the bike. From what I can see, the cylinder appears to be new, along with the starter. I did a compression test and it is a little high (74psi) Book says 71.7 is max. I can't see this little bit causing the problem, but I could be wrong. Last thing is that the idle is a little high. I have tried everything to get it to slow down with no avail. When I put it in gear it will jump slightly and is hard to get back into neutral due to high RPM's. Any Ideas or suggestions will be greatly appreciated.

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Have you checked for an air leak into the manifold? Perhaps a vacuum hose or charcoal canister if it has one?

I'd check the manual's wiring diagram and see if there is a starter feed into the ecu. A lot of things tell the ecu they are cranking to set the timing and fuel to fixed values because the sensors aren't accurate at cranking speeds and voltages. A lack of that feed could cause it to be trying to start with too much advance or a lean mixture.

The ecu and the eps computers are interconnected so the eps codes might be interfering with the engine, or the engine problem might be causing the eps codes. Both problems need fixing.

I'd do a standard tune, check the filters, valve clearances, sparkplugs, ignition timing, vacuum hoses, then clear all the trouble codes and test it again and then look into the eps codes. 

It might pay to check the earths and the power wires going into the ecu and the eps control unit. There are probably more than one power and more than one earth going into each. Earths and power are both common to both circuits...  

Also.. that figure of 75 is too low for compression.. it's probably meant to be 175..

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Yup, seventy pounds and they are hard to start..  Trickily though, the service manual says seventy something pounds max as the compression pressure.. but then right there it also says it's ten to one compression ratio.. 

Perhaps the max is meant to be 175, or, 75 is the minimum not maximum.. which would make more sense.. to quote a minimum pressure..

But Sha.. regardless...  it said one of those trouble codes was the idle speed control, and that could be all the problem is.. I couldn't find the other code in the book I was reading, but it might be a problem caused by the isc..  it might come right once the bike idles again..

They make spray in a can for cleaning idle speed controls..  I've never used it but it might be worth trying that if you don't fancy taking the valve off and cleaning it.

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I think though that computer only sets codes for electrical problems, like broken wires, and doesn't come to conclusions such as  the isc is gummed up..  It might, but I doubt it..

I'd clean the isc to be sure, because they do get gummed up, but then I'd check the isc valve electrically. You need to trace or read a wiring diagram and find the isc wires at the control unit, then check for continuity from there to the isc, and back again if possible all in one continuity test, so that you will have checked the two wires and the plug at each end and that it's contacting the isc properly..

 

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Mech, Thank you for your responses. So lets start from the codes. The EPS system on this bike has its own coding system separate from the engine coding system that displays on the screen. I followed the procedure to pull codes from the EPS module because the EPS light is staying on. That's where those codes come from. According to the manual, those codes mean say low power to EPS module and welded contacts in the EPS module relay. I have checked the power going into the module which is same as battery (Brand new AGM battery). I also have tested all relays in the system. I also removed the IAC module and cleaned it good. It wasn't really too bad. However, I did do a few test starts with it completely removed and it started every time that way. Just idled up very high. So this could still be the culprit. This bike has the Auto Compression Release. Could this be why it states to only have 71.7psi Max? The bike runs great when its running. No smoke or lack of power at all. Oh, and when I go into diag mode on the display, there are no codes. Other than codes from when I ran it with a sensor or module unplugged.  Then it would throw a code, but will clear itself once plugged back in. I have the idle adjustment screw backed out as much as possible and the cable adjustment so that there is slack in the throttle. It should idle down lower than it is. So this does lead me to believe that the IAC is a problem. I just hate replacing parts for no reason. Which is why I came here for further advice, before becoming a parts changer.

IMG_5575.jpg

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Ok, sounds like you have a good handle on it.  I'm just generalising.. Putting thoughts out for your consideration.  

Yeah that low max compression probably is to check the decomp against. It's a 10:1 compression ratio so should have heaps of pressure running.

I agree with you that it seems unlikely that the eps would cause the hard starting, but I wouldn't be surprised if the hard starting problem might set the eps codes. If the starter is straining it could be lowering the battery voltage too much momentarily and setting one of those codes. 

So.. on cars those isc get gummed up.  That could contribute to the hard start and straining starter.  If there are no engine codes set then it's probably not an electrical problem, so a stuck actuator would be a suspect. 

And both those codes do relate to the eps ?  The book I had didn't have the eps in it. From other reading though I'm pretty sure the eps and the ecu communicate. An electrical fault in one system might upset the other. If getting it to idle doesn't fix things, then as a general rule, if we have problems in two different systems we should always look for things in common, such as power supplies or earths. In cars it's a common circumstance that no codes get set for bad power supplies or bad earths, the modules just aren't set to detect or code that. In older cars, if there's a problem and no codes get set we get told to check for stuck or out of range components or bad earth/power wires. It's also pretty vital that after or during testing of components we test the wiring too. The easiest and quickest way to do that is to test from the control module's plug to the sensor/actuator involved and back to the module (if that's how the circuit goes). 

If you've checked all the sensors and actuators and the wiring, most manuals say to try a new or known good module. Perhaps you could borrow one off a buddy's bike or fit the suspect module to another bike. 

Hopefully though, the eps will all be a false alarm. 

Feel free to run any other thoughts past me. Sometimes just talking it through helps. 

 

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Yes compression numbers are low because of the decompression system.

You should never mess with the throttle speed on an fuel injected atv. If engine idle is not within spec then there is something wrong. There should always be a small amount of free play with the throttle but this does not seem to be the problem. The problem is most likely the iac valve or a vacuum leak

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  • 2 weeks later...

Ok, Update on this problem.  I have cleaned the IAC, it was perfectly clean to begin with. Started the bike with it out and watched it function. Seems to be working as designed. I replaced the TPS, I did a test on the OHM reading while rotating it from open to closed. I used a meter with a graph. The signal would spike up and back down at one point in both directions. Everything else tested good. With the new TPS I have been able to get the idle to calm down a little. However, it sill has the hard start periodically. It is a strange issue, the majority of the time, it will start just fine. When it does decide to act up, it will pop and just sound horrible, but once it starts, it runs great.

As far as the EPS codes, yes they are only for that module. It stores its own codes separate from the ECM.  I've read that the speed sensor will cause these issues as well, but it passes every test in the book perfectly. I'm going to do OHM tests on every wire in that part of the system and see of anything seems out of wack. Seems like it has to be a wiring issue maybe. The issue is so random though. It will do it on cold starts sometimes, but mostly after warmed up.

The throttle cable is adjusted with about 1/8" of free play as well. Diag reading on the TPS is between 15-20.

For some reason I still keep wanting to say valve adjustment, but I have already checked them twice. Unless my manual is giving me the wrong specs....

battery is brand new, starter does not dragging or straining at all. When it has the issue, it sounds just like the timing would be off or valves would be out of adjustment. Sometimes backfiring in the exhaust.

I will update with any findings in the wiring system. If nothing is found there, I will have to think that it is the EPS issue causing everything. Which is not a good problem. The module is about $800. I wish I had a spare to plug in and try. I don't know anyone with the same bike anywhere near me.

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Yup well that spike in the tps wasn't right so good work on finding that. The trouble is it didn't fix it so now you have to explain it to the customer.. And that of course is why it's so important to be professional and do things systematically, which it sounds like you are. We always have to be able to explain, and justify, our practices and methods. it's what being professional is all about. You sound professional and shouldn't have any trouble but if you do, send them in here and I'll vouch for your methods and thoroughness.

That throttle reading of 15-20, if that's at idle it sounds a bit much to me.. I'd have thought 20 percent throttle was quite a lot. Most efi throttles with a bypass isc are almost completely shut at idle because they have the isc to let air in. Every throttle body I've seen the set up was for the butterfly to be closed as much as it can go without actually touching the bore too hard which can cause wear and jambing. I'd suspect the throttle sensor needs a move, unless the book says that's the right reading ?

Up further I mentioned a starter feed into the ecu.. Have you looked into that ? The sensors aren't accurate at cranking speeds, or cranking voltages. They set the timing and fuel at fixed values at starting while the start feed gets fed in. If the timing is trying to work off a trigger coil that's not putting out enough power it can throw the timing right out. Same with the airflow or map sensor.

Some wiring issues we can find by letting the bike idle and then go around wriggling the wires hoping it will falter. That's not going to work so well with the start feed into the ecu but it might be worth a try. If you confirm it has the start feed, you could perhaps improvise a feed and try it. And I suppose you already know, most wires break at the ends, where the wire goes into the metal terminal at the plug. That's the place to wriggle.

It's a bit of a long shot and unlikely but, if it's a two cylinder, check nobody's swapped the injector wires over. They still run like that but give hard starting, with backfiring, mostly out the inlet,  and poor performance, but only slightly poor performance. Once you get them started it's hard to tell they are swapped..

And about the only other advice is to always check the sensor readings right at the ecu whenever possible. It helps eliminate wiring problems straight off. 

I'll be interested to hear what this is eventually. To me, this is interesting.. Haha.  

 

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Ok, So wiring it testing good to TPS and Speed Sensor. I did some more testing on sensors and found that the speed sensor is out of spec. Which is most likely the issue with EPS. However, I still do not see anything anywhere that says this would cause the hard start issue. I even unplugged the sensor completely and started it. I acts the same way. So I moved on to the pick up coil. The manual says it should have 459-561 OHMs. I'm getting 601 OHMs. Also, should there be continuity between either of the pick up coil wires and ground? I'm getting 10-12K OHMs there. The manual does not specify this test, but I believe there should not be any contact to ground on that coil. This may be the whole issue.

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I wouldn't think there should be any connection to ground if it has two wires. And if one of the two wires was an earth, and it had an internal earth as well by design, then there shouldn't be that 10-12k reading.

You're a thorough bugger.. Good onya.

Have you checked about that starter feed.. that will do this hard start and backfire thing..

 

What years the bike Sha.. I'll get a manual and have a read.

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I’m not sure where to look to find the starter feed you are talking about. I’m not seeing it in the manual. It’s a 2010 Grizzly 700 FI EPS 4WD. I have a 2004 Grizzly 660 in my shop as well. I tested the pick up coil on it. There is no continuity between the frame and either wire on this one. Which leads me to believe that is most likely my problem. It just isn’t faulted bad enough to prevent the bike from running once it’s started. Also, makes sense that it gets worse once it’s warmed up. It will fail completely soon if not replaced.

 

Thank you for all of your input. It’s nice to be able to bounce ideas to other people and get feedback. I enjoy a good challenge. It is very satisfying once it’s solved. I will update with any new info. 

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You are right, the thing will probably start misbehaving when it gets warm.

If there is a starter feed it will just come off the starter solenoid wire somewhere.. It's on just about every car, and, of all the bikes/quads, yamaha alone seem to do it with their cdi ignitions too.. even on carby models. They must retard the timing I think on the carby models. 

I'll get a manual and see what I can see.

I've always enjoyed mechanicing.. it is a challenge and there are rewards, not least being able to help people. I worked in rural communities and everyone knew me, and that I was honest and sincere and could be trusted, and I used to be honored to have their confidence too when they were broke, or had domestics, or health issues. I've been helping people with all their troubles nearly all my life(now I'm old Haha).

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I found a wiring diagram and it does show the starter circuit's connected into the ecu. The starter solenoid has power to it, then the start button earths it for crank. The wire going to the start button though branches and goes into the ecu as well, which means the ecu has 12 volts showing at that wire until you press the start button, and then the voltage gets dropped as the start button earths that line out. It's pretty foolproof. If the wire broke the ecu would think the starter was being operated all the time and so lock the timing and mixture. Then the engine would run like crap, all the time.

It won't be your problem..

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  • 1 month later...

Just wanted to give a final update on this bike. Nothing I tried solved the issue. Leads me to believe that the only other problem could be the ECU module or the EPS module.  The customer did not want to spend the $800+/- to test the theory. I really hate unsolved mystery, but I gave it my all. Sorry I couldn't come back with a positive update.

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Yup, I'd hate that too.. That's even worse than inadvertently curing a problem, but not knowing what it was you did that cured it, or if it's a permanent cure. 

Second hand unit ?

Take the unit out and to a quad shop and ask if they could plug it in and try it on a good bike ?

All the manufacturers say to test every component and the wiring in the case of a suspect ecu, then if nothing is wrong, try a known good unit or swap the suspect one into a good vehicle. Not so handy for guys like you and I..

 

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Yeah, I asked around here locally and no one had the same bike for me to do the swap with. That would have been ideal. On the more common models that I work on, I have a spare ECU that I can do a quick test and see if that is the issue. This bike wasn't something I see around here very often. I picked up a tote full of ECU's and other misc. electronics from a shop that was closing down. Got that and several other useful items for a good price.

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It's getting to the stage where we need to be able to connect our laptops to the bikes. I've been doing it for years on cars but bikes are not well supported regarding the addresses we need to query. It will come though, plenty of people picking away at it, and every now and then some helpful bike shop employee borrows the scan tool and downloads some bike specific addresses which often do other models as well.

If we can do it, connect to a bike, that's the way to find these problems. A keen man (or woman), with a laptop, can tell more then the half trained parts fitter "technicians" using the factory scan tool.

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