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Discussion Starter · #1 ·
Hey all! I have a 98 sh h22a4 with about 168k. I make 204 wheel and 170ish f/p. I have basic bolt ons (intake, exhaust, headers), a tuned ecu (s300v3) and mishimoto fans and rad. There’s some other smaller mods but I’ve been through all of the basic and intermediate maintenance. Only things I haven’t been through are the harness, bottom end, and trans. Anyways, I’m having an issue with a random misfire at idle and acceleration through about 2500 rpm’s. I’m also having trouble getting my fans to turn on as well as a weird temperature creep while I’m on the freeway driving normal but it stays cool when I drive hard. I have refreshed plugs, wires, distributor, coil pack, water pump, headgasket, thermostat, maf, tps, and I’m on proper timing etc. I’ve replaced the coolant temp switch and sensor and got new fans and get intermediate power randomly but mostly not. I also am running ridiculously rich (like 12:1 at idle) which I think could be the cause for misfire as I start to lean out through higher rpm (thanks hondata for the info). I have no trouble codes and no sensor faults on hondata. I’m suspicious that these problems are from one underlying electrical issue. If anyone has any insight on the specifics of the h22 harness that I should know please give me a shout. I’m not very auto electrically oriented so go easy on me lol. I don’t think my issues are consistent enough to be a bad ground, but I feel like there could be an open or wiring issue somewhere around the thermostat area.
Thank you so much for helping or even reading. It means a lot. This has been really frustrating and I just want my car to run strong.
 

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The fan switch on your thermostat housing is probably your fan problem. Common failure, but not the cause of your misfire.

I would still be looking at mechanical side for the rest.

When you did your headgasket, did you properly check the deck for warpage?
Did you have the head resurfaced?
Did you have a valve job done?
When is the last time you adjusted your valves?
Have you done a vacuum test?
Have you done a compression test?
Have you done a leak down test?

On the electrical side..... The wiring harness itself is usually well made with little issue unless it has been neglected or not secured properly leaving it to rub against sharp corners or brackets.
You have a tuned ecu, but did you have the car itself tuned? A rich condition at low rpms can easily cause misfires.
You can use an oscilloscope to verify crank, cam, and fuel injector patterns. This will identify any signal problems.

Also, these vehicles use map sensors, not a maf.
 

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Discussion Starter · #3 ·
Thanks for your response Faulcan! And yes I rebuilt the head, as well as had it resurfaced. So valves are good. As for compression it’s lower but consistent at about 190. I also performed a leakdown test and found no red flags. I also am not exactly sure what you mean by tune the car? As well as what you mean by signal problems. Also the fan problem; I’ve replaced the switch twice and have checked fuses and relays. All pass individual testing. But when put all together to form the system it doesn’t work consistently. As if it has a mind of its own. Again, thanks again and if there’s anything else I can address/check please throw it at me.
 

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Discussion Starter · #4 ·
The fan switch on your thermostat housing is probably your fan problem. Common failure, but not the cause of your misfire.

I would still be looking at mechanical side for the rest.

When you did your headgasket, did you properly check the deck for warpage?
Did you have the head resurfaced?
Did you have a valve job done?
When is the last time you adjusted your valves?
Have you done a vacuum test?
Have you done a compression test?
Have you done a leak down test?

On the electrical side..... The wiring harness itself is usually well made with little issue unless it has been neglected or not secured properly leaving it to rub against sharp corners or brackets.
You have a tuned ecu, but did you have the car itself tuned? A rich condition at low rpms can easily cause misfires.
You can use an oscilloscope to verify crank, cam, and fuel injector patterns. This will identify any signal problems.

Also, these vehicles use map sensors, not a maf.
Please read previous post^^^^
 

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I also am not exactly sure what you mean by tune the car?
There is a difference between plugging in an ECU that has a basemap loaded on it for the mods installed on your car, and actually taking the car to a dyno and having it tuned in real time for the specific conditions that exist for the vehicle. Also, you know that by running anything other than the factory ecu on the SH, your ATTS system does not function.

As well as what you mean by signal problems.
Your engine is controlled by your ECU. Well, how does it do that? It gets fed information from various sensors. Each sensor outputs a signal pattern that the ECU reads. It then tells the ignition coil and fuel injectors when to fire. Injectors are two wire controlled, power and ground. This produces an on/off signal that looks something like this:
Rectangle Slope Plot Font Line



And a crank signal looks something like this:
Rectangle Font Display device Electric blue Parallel


You can identify problems with the signal by setting up correctly and viewing patterns like this. If your signals look good, then your problem isnt in the wiring, or the things controlling the components that the wires go to.


Also the fan problem; I’ve replaced the switch twice and have checked fuses and relays. All pass individual testing. But when put all together to form the system it doesn’t work consistently. As if it has a mind of its own.
So, the fan switch system is easy to check. First, make sure the ground located nearby is clean, the bolt is clean, and the surface it contacts is clean. By clean, i mean take sand paper to it.

Next, unplug the connector, turn your ignition to ON, and check for battery voltage on the GREEN wire. If no power, check fuse 9 in the underdash fuse block (7.5a)
If power is good, take a piece of spare wire and jump the connector. Both radiator fans should turn on.

If the all the tests work properly, then the most common problems are either
A: the coolant system was not burped correctly and you have a massive air pocket stuck in the housing (make sure you use, at minimum, a spill free funnel, and turn on your heat while burping the system so you get the air pocket out of your heater core)

or

B: The thermostat was installed backwards (wrong end toward the water pump) or upside down (with the pin hole not at the 12 o'clock position not allowing air to move out of the system while the thermostat is closed during burping)
 

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Discussion Starter · #6 ·
There is a difference between plugging in an ECU that has a basemap loaded on it for the mods installed on your car, and actually taking the car to a dyno and having it tuned in real time for the specific conditions that exist for the vehicle. Also, you know that by running anything other than the factory ecu on the SH, your ATTS system does not function.



Your engine is controlled by your ECU. Well, how does it do that? It gets fed information from various sensors. Each sensor outputs a signal pattern that the ECU reads. It then tells the ignition coil and fuel injectors when to fire. Injectors are two wire controlled, power and ground. This produces an on/off signal that looks something like this:
View attachment 20200


And a crank signal looks something like this:
View attachment 20201

You can identify problems with the signal by setting up correctly and viewing patterns like this. If your signals look good, then your problem isnt in the wiring, or the things controlling the components that the wires go to.




So, the fan switch system is easy to check. First, make sure the ground located nearby is clean, the bolt is clean, and the surface it contacts is clean. By clean, i mean take sand paper to it.

Next, unplug the connector, turn your ignition to ON, and check for battery voltage on the GREEN wire. If no power, check fuse 9 in the underdash fuse block (7.5a)
If power is good, take a piece of spare wire and jump the connector. Both radiator fans should turn on.

If the all the tests work properly, then the most common problems are either
A: the coolant system was not burped correctly and you have a massive air pocket stuck in the housing (make sure you use, at minimum, a spill free funnel, and turn on your heat while burping the system so you get the air pocket out of your heater core)

or

B: The thermostat was installed backwards (wrong end toward the water pump) or upside down (with the pin hole not at the 12 o'clock position not allowing air to move out of the system while the thermostat is closed during burping)
So the tune was on a dyno done by a performance shop in my area (Portland), and it came out great for the first month or so before problems arose. I payed extra prior to the tune for diag to ensure I didn’t have any problems like this. And I’m fairly certain the thermostat is in place correctly as I did that multiple times. The system was burped on numerous occasions to ensure thoroughness. I also noticed that before (not exactly sure when before is but I know it used to be) I could manually turn on the ac fan. But not neither of them come on even when I have the ac and I’m at op temp.
 

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Discussion Starter · #7 ·
There is a difference between plugging in an ECU that has a basemap loaded on it for the mods installed on your car, and actually taking the car to a dyno and having it tuned in real time for the specific conditions that exist for the vehicle. Also, you know that by running anything other than the factory ecu on the SH, your ATTS system does not function.



Your engine is controlled by your ECU. Well, how does it do that? It gets fed information from various sensors. Each sensor outputs a signal pattern that the ECU reads. It then tells the ignition coil and fuel injectors when to fire. Injectors are two wire controlled, power and ground. This produces an on/off signal that looks something like this:
View attachment 20200


And a crank signal looks something like this:
View attachment 20201

You can identify problems with the signal by setting up correctly and viewing patterns like this. If your signals look good, then your problem isnt in the wiring, or the things controlling the components that the wires go to.




So, the fan switch system is easy to check. First, make sure the ground located nearby is clean, the bolt is clean, and the surface it contacts is clean. By clean, i mean take sand paper to it.

Next, unplug the connector, turn your ignition to ON, and check for battery voltage on the GREEN wire. If no power, check fuse 9 in the underdash fuse block (7.5a)
If power is good, take a piece of spare wire and jump the connector. Both radiator fans should turn on.

If the all the tests work properly, then the most common problems are either
A: the coolant system was not burped correctly and you have a massive air pocket stuck in the housing (make sure you use, at minimum, a spill free funnel, and turn on your heat while burping the system so you get the air pocket out of your heater core)

or

B: The thermostat was installed backwards (wrong end toward the water pump) or upside down (with the pin hole not at the 12 o'clock position not allowing air to move out of the system while the thermostat is closed during burping)
Also this has been super awesome. You seem so knowledgeable and I’m so grateful.
 

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If you are sure the system was burped properly and all that, do the tests i suggested on the fan switch

I could manually turn on the ac fan. But not neither of them come on even when I have the ac and I’m at op temp.
Explain this better

Edit: I have a 99 SH that i built from the ground up, and am rebuilding it again. I also own and operate a repair shop :)
 

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Discussion Starter · #9 ·
Explain this better

Edit: I have a 99 SH that i built from the ground up, and am rebuilding it again. I also own and operate a repair shop :)
[/QUOTE]
Usually when you press the A/C the fan closer to the passenger side turns on. And it used to do that every time. Now it doesn’t do it at all. Also I’ll test the fan switch.
 

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Usually when you press the A/C the fan closer to the passenger side turns on. And it used to do that every time. Now it doesn’t do it at all. Also I’ll test the fan switch.
Ok that changes things a little bit. Lets see what the fan switch tests come up with first, and we'll go after it with this new information
 

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Discussion Starter · #11 ·
The fan switch on your thermostat housing is probably your fan problem. Common failure, but not the cause of your misfire.

I would still be looking at mechanical side for the rest.

When you did your headgasket, did you properly check the deck for warpage?
Did you have the head resurfaced?
Did you have a valve job done?
When is the last time you adjusted your valves?
Have you done a vacuum test?
Have you done a compression test?
Have you done a leak down test?

On the electrical side..... The wiring harness itself is usually well made with little issue unless it has been neglected or not secured properly leaving it to rub against sharp corners or brackets.
You have a tuned ecu, but did you have the car itself tuned? A rich condition at low rpms can easily cause misfires.
You can use an oscilloscope to verify crank, cam, and fuel injector patterns. This will identify any signal problems.

Also, these vehicles use map sensors, not a maf.
I figured it out, one of the plugs insulators cracked. Not sure why. Never ran hot and they were brand new. I also got a new Honda oem temp switch that did the trick. It was just me overcomplicating everything instead of starting with the basics. Thank you again.
 
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