Performing Honda K24a3/AST5 6spd Conversion

[kmead]

- a little too easy to get up around 100, so I will have to be very careful once I am driving it routinely.

Hmmm, such a surprise

Getting to a proper idle is important as a stalling engine is a real safety issue. Bummer it also affects the lower to mid throttle response. I have the lower hp version of this engine in my Honda Element and really do like its behavior overall, I believe the version I have is designed to enhance the torque versus high hp which makes it pretty driveable despite being in a heavy box. My other Element (we have two now) had an issue with the cam advance system going into limp mode which was frustrating to solve (they really like clean oil and the right oil level which the past owner apparently failed to understand) and a huge drivability issue.

Sorry the teething is proving so frustrating.

 

[PaulD]

-

Sorry the teething is proving so frustrating.

If the issue is in your engine management system, it may make sense to let your tuner have at before the dyno run. Unrelated but parallel was my difficulties in setting the idle with my AEM system. There were at least 15 tables that would effect the idle (with each impacting the others), and I was completely flummoxed by it. My tuner was very knowledgeable, and had it dialed in quickly.

The trick in doing this is assuring that there are not other mechanical or sensor factors that are part of the problem before it goes to the tuner. You have done vacuum leaks, are working on the IAV, and done a number of the sensors. Perhaps the TPS?

Paul

 

[lookforjoe]

- a little too easy to get up around 100, so I will have to be very careful once I am driving it routinely.

Hmmm, such a surprise

Getting to a proper idle is important as a stalling engine is a real safety issue. Bummer it also affects the lower to mid throttle response. I have the lower hp version of this engine in my Honda Element and really do like its behavior overall, I believe the version I have is designed to enhance the torque versus high hp which makes it pretty driveable despite being in a heavy box. My other Element (we have two now) had an issue with the cam advance system going into limp mode which was frustrating to solve (they really like clean oil and the right oil level which the past owner apparently failed to understand) and a huge drivability issue.

Sorry the teething is proving so frustrating.

Yeah- pretty sure the Element variant, like the Accord versions are tuned for economy & only have VTEC on the exhaust side. It's a nice motor though. I'd had the cam (VTC) go into limp mode several times - just goes completely flat under acceleration. With my K24A3 (same as US K24A2, int & exh VTEC), it is due to the intake VTC advance mapping. The tuner will resolve that, for now I've just limited the low cam mapping to under 30º.

 

[lookforjoe]

Reinstalled the old ECU, reset & unlocked (again), then reinstalled new ECU & locked it to the user board. After that, I was able to properly register & upload my tune to it.

Replaced the VTEC solenoid seal, old one had a couple breaks. Torqued to 104in/lb.

Made a manual idle control using the dead IACV, until I can get to the tuner, I can't find anything wrong with any of the input signals or wiring.

After that, I worked on the AC fittings.

Low side extension

High & Low cut & braised

Low side is run behind the hinge for now - may need to move it back out though

Drew down the system for an hour, after checking it held vacuum. Added oil & 24 oz freon, compressor wouldn't turn on, so I bypassed the low pressure switch to check the wiring & compressor. Need to add more freon to overcome the low pressure cut off. Should be 35-40 low side, according to Fiat manual (EDIT; 25-30 for R134a)

also, in cleaning up the refrigerant oil off the fuel rail & injector plugs, I found that the engine developed a miss when I moved two of them (!), so I need to remove the adapter harnesses for the RDX & repin the factory harness for the RDX connectors.

 

[ng_randolph]

Drew down the system for an hour, after checking it held vacuum. Added oil & 24 oz freon, compressor wouldn't turn on, so I bypassed the low pressure switch to check the wiring & compressor. Need to add more freon to overcome the low pressure cut off. Should be 35-40 low side, according to Fiat manual

I am guessing you are using R134a, and not R12 ("Freon"). The operating pressures for R134a are different from those for R12, so most of the numbers in the Fiat manual won't apply. If you compressor is not made by Sanden, odds are it is a Chinese knock-off of a Sanden unit, so I would suggest having a look at the Sanden web site. They post a lot of good information, so you might be able to find appropriate operating pressures etc. there.

I have heard said that R134a systems are a bit finicky to charge, and I've seen suggested measuring the amount of refrigerant you put in rather than trying to get the pressures right during charging. To do this, you would need to know the total system volume (adding up volume of all the piping, condenser, evaporator, receiver, compressor etc.).

 

[lookforjoe]

I am guessing you are using R134a, and not R12 ("Freon"). The operating pressures for R134a are different from those for R12, so most of the numbers in the Fiat manual won't apply. If you compressor is not made by Sanden, odds are it is a Chinese knock-off of a Sanden unit, so I would suggest having a look at the Sanden web site. They post a lot of good information, so you might be able to find appropriate operating pressures etc. there.

I have heard said that R134a systems are a bit finicky to charge, and I've seen suggested measuring the amount of refrigerant you put in rather than trying to get the pressures right during charging. To do this, you would need to know the total system volume (adding up volume of all the piping, condenser, evaporator, receiver, compressor etc.).

Thanks for the input.

MY compressor is a Diesel-Kiki KO - Volvo application of course, I had bought it to put in my old wagon & never got around to it.

I found a pic I took of the operating pressures last time I charged the R134a conversion with the LarryC AC condensor change. I understand pressures are also temperature dependent, however my recollection of needing to see a low side in the 25-30 range is correct. I think 35-40 (from the Fiat manual) is too high.

 

[stingray250]

If the issue is in your engine management system, it may make sense to let your tuner have at before the dyno run. Unrelated but parallel was my difficulties in setting the idle with my AEM system. There were at least 15 tables that would effect the idle (with each impacting the others), and I was completely flummoxed by it. My tuner was very knowledgeable, and had it dialed in quickly.

The trick in doing this is assuring that there are not other mechanical or sensor factors that are part of the problem before it goes to the tuner. You have done vacuum leaks, are working on the IAV, and done a number of the sensors. Perhaps the TPS?

Paul

Smoke machine is your friend....

 

[lookforjoe]

Smoke machine is your friend....

Yes - I have one

With the idle valve port blocked off the idle is perfect, in terms of stability & rpm. The problem is, if I drive it that way, the system tries to make adjustments whilst underway that result in jerky throttle tip-in, and in some cases stalling when coming to a brisk stop.

I seem to have come to a happy medium with my modified manual IACV in the sense that I can open it on first start, then close it (mostly) after 30sec-1min, and it will drive OK that way with no stalling. Still have the jerky tip-in on occasion though.

Anyway, I now feel like I'm smelling burnt coolant. No sign of coolant loss, but on first start does seem like much vapor. But... the ambient temps are still low, so vapor is to be expected, IMO. No evidence of coolant slime on the tailpipe. I'll have to go to the garage I have access to & borrow their coolant sniffer.

I replaced the injector terminals today, to eliminate the adaptor harnesses for the RDX injectors. Used the sockets from the adaptor harness, & replaced the harness terminals. Figured out they were TS 090 series, which I have.

 

[lookforjoe]

Stopped at the garage & used the coolant sniffer - no evidence of CO2 in the coolant. I did make the mistake of opening the reservior too soon after stopping, so that introduced air into the system. Had to spend some time bleeding & adding coolant back after I got it home.

This is where I'm at with the AC - I removed the line I made with the seeping beadlock, and re-crimped it. Nothing to lose, I did order new fittings to make another line, but I figured I'd give this a try. Weather was warm & sunny so I was able to work in the drvieway in a tee-shirt

Repaired line

I drew down the system for about 40 mins, then left it sit. Held vacuum with no problem, so I started adding freon. Compressor didn't want to kick on, so I jumped it & then it sucked in the first can. Shut it off & reconnected the low pressure switch, and the AC kicked on upon restart.
Hooked up the 2nd can - took some & then seemed to just stop. I couldn't even get 24oz in the system, it just seems to stop taking any more. Makes no sense to me. I tried shutting it off, restarting, raising RPMS, didn't really change. The system is getting cold, and these are the pressures I have at idle, so I'll just leave it be for now. At least I have confirmed my modded system is operational.

duct temp, dropped to 40 when moving. Ambient temp was only 70, though.

 

[TonyK]

Hussein, the pressures look good. I would not charge it with any more gas than that. 30 degree differential is about the norm, but could be a bit more. Air flow over the condenser is the biggy. A moving vehicle sees more air flow than the fans running.

Did you look at the expansion valve if it was frosting or not. I have seen my return line totally frosted up, which tells me that I am not getting enough air flow over the evaporator to prevent the frosting from happening. Nice work on the car in general. Swaps can be a challenge, nice to see you work through the issues one by one.

TonyK.

Grimsby Ontario Canada.

 

[lookforjoe]

Hussein, the pressures look good. I would not charge it with any more gas than that. 30 degree differential is about the norm, but could be a bit more. Air flow over the condenser is the biggy. A moving vehicle sees more air flow than the fans running.

Did you look at the expansion valve if it was frosting or not. I have seen my return line totally frosted up, which tells me that I am not getting enough air flow over the evaporator to prevent the frosting from happening. Nice work on the car in general. Swaps can be a challenge, nice to see you work through the issues one by one.

TonyK.

Grimsby Ontario Canada.

Thanks Tony - I don't have an expansion valve anymore, I switched to orifice tube/ accumulator setup.

I didn't wrap the hot side yet (to seal the switches for reading the line temp)

My expansion valve is simply a pass through elbow now, I drilled it out to full ID. I did wrap them with butyl. I will have to pull back the butyl to feel the line temp.

 

[lookforjoe]

Found that moving the suction side behind the hinge was indeed a problem. Not enough slack, basically the engine movement undid the fitting.

So, I moved the hose back to the motor side of the hinge, and repositioned the two hoses. I tied them together to stop them moving independently. I may need to remake both hoses and move them to provide more flex. At the very least, I need a sturdy clamp to keep the two hoses rigidly tied. Low side has clearance in the flex area after the hinge, but it is pressed into the hinge.

duct temps are good, frosty suction side hoses & accumulator.

EDIT: Ordered a couple of variants of Compressor beadlock hose fittings that will hopefully allow a more stress-free fit along the bulkhead.

 

[TonyK]

Hussein, let's look at this a bit more. When the accumulator was frosted like in the picture was the expansion valve picture taken at the same time? I know now that you have an expansion tube, but frost should be starting there. Two things come to mind. If the frost is from the expansion tube to the accumulator then you do not have enough air flow over the evaporator. If the frost is not at the evaporator lines but is at the accumulator, you have too much charge in the system and the bulk of the expansion of the gas is happening after the evaporator in the return lines and accumulator. Keep in mind that the ambient air temperature will have some affect on all of this as well.

Just one other thing that I have noticed with bead lock crimps, from time to time you may see one leak at the hose crimp, install the next smaller die in the crimp set and give it a bit more crimp. some of the hoses and some of the fittings have just a bit different diameter and the crimp needs just a bit more on it to get a correct seal. I have had this happen a few times and recrimping with a smaller die has solved the problems.


TonyK.

Grimsby Ontario Canada.

 

[kmead]

So it seems like there are two approaches to this.

Reduce the distance from the 90° connections on the compressor to the 90°hose connection to pull the hoses tight to compressor bracket with a retention bracket going over the hoses to hold them there and protect them from chafing.

I actually think this approach is likely to end in a different failure over time which is that there will be enough movement of the engine that you will fatigue the hose ends or other connections as there isn’t much compliance in the hose runs you have beyond the engine. Clearly this is an opinion and I have been wrong before.

The more I look at your install the more I tend to think you should consider running around the opposite side of the compressor, over the cam cover and then to the connections on the far side of the engine. By rotating the accumulator @45-60°counter clockwise the connection would allow you to have a good approach from the cam cover side and the other hose could be one piece from the lower bulkhead up and around the accumulator and then over the cam cover. Adding a retention bracket to the flex hose above the vertical bulkhead connection would keep from work hardening the rigid line going down into the tub of the car.

I know the second option isn’t as clean but it should afford enough room for the hoses and keep them from being crushed chafed and so on. I think it would also ward off work hardening the aluminum piping as the engine moves under load from taking advantage of the significant power you now have available.

 

[lookforjoe]

Hussein, let's look at this a bit more. When the accumulator was frosted like in the picture was the expansion valve picture taken at the same time? I know now that you have an expansion tube, but frost should be starting there. Two things come to mind. If the frost is from the expansion tube to the accumulator then you do not have enough air flow over the evaporator. If the frost is not at the evaporator lines but is at the accumulator, you have too much charge in the system and the bulk of the expansion of the gas is happening after the evaporator in the return lines and accumulator. Keep in mind that the ambient air temperature will have some affect on all of this as well.

Just one other thing that I have noticed with bead lock crimps, from time to time you may see one leak at the hose crimp, install the next smaller die in the crimp set and give it a bit more crimp. some of the hoses and some of the fittings have just a bit different diameter and the crimp needs just a bit more on it to get a correct seal. I have had this happen a few times and recrimping with a smaller die has solved the problems.


TonyK.

Grimsby Ontario Canada.

Thank you for the advice, Tony.

I will have to check - I didn't look at the expansion tube. I think it was more to do with the ambient temp. I didn't get even 24oz in there before the pressures were in the 20/250 range, with good duct temps, so I left it at that for now.

I did re-crimp the hose I had seeping - I didn't think to use the smaller die set - so I will keep that in mind if/when I need to revisit any of the lines I made.

 

[lookforjoe]

So it seems like there are two approaches to this.

Reduce the distance from the 90° connections on the compressor to the 90°hose connection to pull the hoses tight to compressor bracket with a retention bracket going over the hoses to hold them there and protect them from chafing.

I actually think this approach is likely to end in a different failure over time which is that there will be enough movement of the engine that you will fatigue the hose ends or other connections as there isn’t much compliance in the hose runs you have beyond the engine. Clearly this is an opinion and I have been wrong before.

The more I look at your install the more I tend to think you should consider running around the opposite side of the compressor, over the cam cover and then to the connections on the far side of the engine. By rotating the accumulator @45-60°counter clockwise the connection would allow you to have a good approach from the cam cover side and the other hose could be one piece from the lower bulkhead up and around the accumulator and then over the cam cover. Adding a retention bracket to the flex hose above the vertical bulkhead connection would keep from work hardening the rigid line going down into the tub of the car.

I know the second option isn’t as clean but it should afford enough room for the hoses and keep them from being crushed chafed and so on. I think it would also ward off work hardening the aluminum piping as the engine moves under load from taking advantage of the significant power you now have available.

Hey Karl

If I shorten the elbow extensions, I'm back to the original issue - there isn't clearance off the compressor mounts unless I run the lines above, then they will hit the engine cover.

I'm definitely not running any lines over the motor. The valves have to be adjusted at a regular service interval, and accessing the serpentine would become a PITA for starters. It would also look aesthetically terrible .

The fittings I've ordered are similar to the base elbow I have off the compressor, but the hose is crimped to it, so I won't have that rigid lever that is there now, the hose will arc & have more flex room. I also ordered one 135 degree version for the #10 hose, as that one is harder to arc. with the 135 degree, it would just angle in toward the compressor. I will test fit them & see which gives the more relaxed fit. I want the #10 off the bulkhead as that is definitely a long term issue, besides the annoying vibration transfer.

 

[kmead]

Out of curiousity how often do the valves need adjustment? I am sure they need adjusting on my K24s given the utilitarian it will run forever nature of the past owners, it has never been done.

They certainly don’t sound loud on my cars, do they actually get that far out of adjustment?

I was thinking that if they were flexible lines over the cam cover you could still work with/around them.

Yes it would look bad

Is there a reason you don’t want the hoses tight to the compressor mountings? Heat transfer? It’s a non adjustable object and since they don’t move relative to the hoses no chance of chafing particularly if they are clamped to the side of the compressor.

Sorry I keep harping on something that I can’t solve from afar...

 

[lookforjoe]

Out of curiousity how often do the valves need adjustment? I am sure they need adjusting on my K24s given the utilitarian it will run forever nature of the past owners, it has never been done.

They certainly don’t sound loud on my cars, do they actually get that far out of adjustment?

I was thinking that if they were flexible lines over the cam cover you could still work with/around them.

Yes it would look bad

Is there a reason you don’t want the hoses tight to the compressor mountings? Heat transfer? It’s a non adjustable object and since they don’t move relative to the hoses no chance of chafing particularly if they are clamped to the side of the compressor.

Sorry I keep harping on something that I can’t solve from afar...

I'd have to check, but I think it's either 15K or 30K intervals. Typically valves get tight not loose as the parts wear, unlike the clack-clack of old pushrod motors.

I had to go back to an earlier post to recall why I messed with them at all If I move the hoses back up against the compressor, they have to be raised, then I'm back with the cover hinge hacking them problem.

Didn't drive it to work today, so I don't know what the status of the AC circulation is yet.

Today I just wired the stereo and the keyless entry.

Have 222 miles on the setup so far. Trying to drive it as much as possible to iron out all the kinks before any long drives. Not going to put the engine cover on until the idle issue is resolved, since I have to manually set the high idle for initial starts, then reduce it after a minute. The system still tries to make adjustments (symptom is idle surge) even though I have disabled every IACV related setting I can find

 

[kmead]

Finally a speedometer that reflects the capability of the actual drive train in the car.

 

[lookforjoe]

Finally a speedometer that reflects the capability of the actual drive train in the car.

Unfortunately, with the 4.7:1 (!!) diff, it taps out long before

I don't understand why on earth it would be geared that way. Our car is so light, we just don't need that tall gearing. I put a 4.10:1 diff from a 16v 740 in a Volvo 245 many years ago to improve off the line pull, and that was tall gearing, this is nuts.