Hi,

I am having a tough figuring out what the hell is wrong with my car. It is 98 prelude h22 with 5 speed. I have no vtec and the redline at 6500 there, i have problem also with the charging system light and CEL light not working.
I have tried 3 different ECU's (2 stock p13 and a p28 chipped with h22 basemap). I have tested the vtec solenoid it is working and i replaced it too, rewired the vtec solenoid and pressure switch. tired to jump A4 to D6 no luck. Changed oil & filter. I hooked up a light to a13 to see if i have any codes got code 6 and replaced ect sensor. reset ecu but nothing.

Any help please am f***** up.

 

A 1998 should be OBDII, so you hook up a code reader via the OBD port. Make sure that you aren't clearing the codes by disconnecting the battery before reading them, but this sounds like a problem that is constant?

When did it start, did anything change, did you buy the car like this, etc?

 

I bought this car from a girl it was auto and I did 5 speed swap. I am using obd2 to obd1 harness.i did try the obd2 ecu too. The car runs normal did compression test all good.

 

vtec doesnt engage until engine is warm enough (faulty temp sensors?).
is there oil in engine? vtec uses oir pressure so if your oil level is too low it cannot engage or if oil pressure sensor is faulty or vtec solenoid is clogged/doesnt work

have you changed your fuel filter ever? cleaned fuel injectors? adjust valves?

compression and leak tests could also tell you something?

 

i replaced the coolant sensors and the vtec solenoid already. Run new wires from the ecu. The oil and filter just replaced. Fuel injectors are good and tested. Fuel filter no, valve adjustment not done. The car runs strong. Will do valve adjustment and see what happens

 

I think you will be chasing random ideas for a long time if you can't find the reason for the limp mode. The ECUs all seem to be doing the same thing correct? That tells me there is an issue in the wiring or sensors that is causing it probably.

Does the Check engine light come on at all, i.e. when you cycle the key to Run position, before starting the car? If not, I would find and fix this issue first, or you are chasing ghosts without even knowing if you have a code or what it is. I had an ecu that would not send a signal to the light, and chased a bad temp sensor for weeks, since the car ran great aside from that. Finally swapped to another ecu and the problem was fixed in 30 seconds once I ran the code and changed the sensor.

You could easily have mixed up MAP and IAB plugs or something simple like that, and it will cause the issue.

 

i checked for codes i got only EGR which is already blocked. I am starting to pulling my hair. I jumped A4 to D6 no luck. The temp sensor already replaced.

 

Pick up some electrical parts cleaner and spray the crap out of the distributor. See if you got any dents in your oil pan. If you got major oil leaks and fix em.

 

i have no dents in my oil pan. I will clean the distributor any see what happens. I also borrowed my friends oil pressure gauge to test the pressure. Will give update tomorrow

 

-CEL during bulb check? (Key-On-Engine-Off)?
-Active codes from ECU read through OBD-II port?
-Sufficient oil pressure for VTEC pressure switch?
-Test operation of VTEC solenoid, VTEC oil pressure switch
-Check all grounds (Sensors can work intermittently do to faulty grounds even if the ECU is sending Battery + or 5v Reference voltage)
-Pin A4 (VTEC Solenoid) should be grounded with key-on-engine-off. So there should be continuity between Pin A4 and ground. There should also be continuity between ground and pin D6 (when the ECU is not "in VTEC", so, key-on-engine-off) So check that with key-on-engine-off you have continuity between ground and each terminal on the connector to the VTEC solenoid.
-About connecting Pin A4 (VTEC Solenoid) and Pin D6 (VTM/VTPS or + Power)... What parameters and what events are required for Pin D6 (VTM/VTPS) to be energized?
-Is the Solenoid being activated when A4 and D6 are shorted?
-Are you shorting A4 and D6 then driving the car to see if VTEC engages? (VTEC requires vehicle speed, oil pressure, coolant temp, throttle position and I believe MAP readings to activate the solenoid)

I'd try and do what others have said and what I wrote, I'm just trying to summarize it, ask questions and stir things up, maybe get more of a troubleshooting process to follow.

 

I had this issue when I bought mine, the previous owner had neglected oil changes and was running 15-40. I dumped in a quarter of marvel mystery oil, let her run at idle for 30 minutes and changedo the oil. It smelt burnt and nastey. Put in 10-30 and she ran so much better. If your oil filter is restricted it won't have the proper oil pressure. If you get it fixed, post your fix.

 

I had a similar issue with my 98' Prelude. I did various trouble-shooting of the vtec system solenoid, sensors, etc from lots of research online but this forum was the most helpful n thats why i decided to join. At the end of the day i had a bad oil pump and thats why my vtec wasnt engaging 100% and thats why i was hitting the 6500rpm redline/limp mode. Remember, vtec is very dependant on oil pressure and if u dont have the proper oil psi at normal operating temp, vtec won't engage completely. Do yourself a favor and take off the oil pressure sending unit behind the block and hook up an oil pressure gauge to monitor your oil psi. I believe you should have 20-30psi at idle and around 50psi at 5000rpm if i'm not mistaken. In my case, my oil pump produced 20psi at idle when cold but as the operating temp reached normal and cycled the cooling fans once or twice, the oil pressure would drop down to 4-6psi at idle and wouldn't go above 25psi after 3000rpm. hope this helps.

 

Here's the post i put up in case u wanna read up in more detail on the issues i was having and what i found along the way. https://honda-tech.com/forums/honda-...links-3287045/

 

Hi guys,

I havent fixed this issue yet. I have good oil pressure because i have a gauge hooked in my car. The things i did so far:

-I have tried 3 different ECU's (2 stock p13 and a p28 chipped with h22 basemap).
-I have tested the vtec solenoid it is working and replaced it with good known one.
-rewired the vtec solenoid and pressure switch.
- Jumped A4 to D6.
- Replace cooling sensors.
- Compression test.
- valve lash.

I dont know what else to do. Maybe some problem with the head?

 

oil pressure sensor/switch?

 

​​​​​​​already replaced. in fact replace the solenoid.

 

you know that vtec solenoid and oil pressure switch are not the same thing?

 

I thought that the oil pressure is screwed into the solenoid? do u mean the oil pressure sender? if yes already replaced it with AEM sender and installed the AEM gauge
​​​​​​​

 

 

I had it replaced with AEM oil pressure switch

 

your story doesnt tell that when this problem started:

did you do something to your engine and after that this happened or did it just suddenly started acting wrong?

 

Do you have any oil leaks ? It's possible for oil leaks to disable vtec. Did you ever clean out the distributor ? It's likely this is going to be distributor related. I would guesstimate it was the vtec solenoid before you said you replaced it with a working one. Even vtec solenoids that test good wind up being the cause of the problems sometimes.

 

I bought this car from a girl. It was auto then I did 5 speed swap. The vtec wasnt wired. So. I wired the vtec sloenoid and the vtec pressure switch and replaced the ecu with p13 manual ecu.

I did clean the distributor and hooked the multimeter to test all the sensors and the coil.

 

Are you saying it runs normal on the stock obd2 ecu with no issues ?

 

Tried obd2 ecu and obd1 ecu same. The car runs normal but no vtec