5th gen Prelude has mechanics stumped…ideas?

[GBL1]

Here's that facts...I tried to keep it simple...looking for ideas of what's wrong. I bet it's something simple, stupid, and easy to fix, but....


2000 Honda Prelude, base model w/ 5 spd manual – 121K miles

Recent tune-up (plugs, rotor, cap, wires, & fuel filter) replaced at 114K miles, v-tec solenoid cleaned out & new rubber gasket installed at 120K miles. Has slight oil leak & power steering leak to be addressed, as I’m able to do so.

Car ran perfect…passed state emissions test on Aug 3rd. Previously threw check engine light code for O2 sensor # 1…only when driving through heavy rain (wet connection?). Reset CEL after rain = no problems afterwards.

Took it in to a shop for timing belt service (I KNOW…recommended at 105K miles) & to have a performance header & catback exhaust installed…kept stock cat in place.

Got car back: ran funny & would not kick into v-tec at 5200 rpm…also had an exhaust leak at header/mid-pipe flange.

Had a Honda dealer tech drive car: he said it ‘may’ be ‘off’ by one timing belt tooth…to the exhaust side if it is.

Returned car to installation shop: they checked it over, said timing was dead spot on, but that two connectors underneath that control timing were plugged in, but not ‘snapped’ fully. Assumed it was just a loose connection. Car runs great now…except for exhaust leak and periodic check engine light coming on (assumed to be O2 sensor # 1).

Removed mid-pipe & determined that one stud was cross-threaded preventing a full, tight seal. Forced to drive car w/ open header for 2 miles during course of the repair…but did not “get on it” at all. Replaced stud & gasket…no more exhaust leak. Added an O2 ‘simulator’ (metal extender sleeve in between sensor & exhaust pipe) thinking that sensor was getting too much from now bigger header pipes.

Car runs & sounds GREAT now (nice deep tone hum to the exhaust) except for “occasional” (about 10% of the time) v-tec not kicking in…car just stutters & sputters at v-tec rev mark (5200 rpms). CEL now coming on regularly after 10-15 minutes of driving. Had code pulled…indicated “O2 sensor # 1: low voltage”. Likely needs to be by-passed or replaced now…

Drive car one mile away after getting code pulled: now stutters & sputters at various rpms…and dies. Car turns over but will not start….as if it’s out of gas, but it has half a tank full.

Waited approx. an hour: car started right up & revved fine. Ran for maybe 15 seconds, then died again…& will not restart. Waited a few more hours, tried again, got same results…car started right up & revved fine. Ran for maybe 5-10 seconds, then died again…& will not restart.

Pulled plugs: appear normal, no indication of fouling. Checked all connections, everything looks fine.

I, an auto mechanic student friend at UTI, his buddy…a mechanic, a current high school auto shop teacher (former tech at a car dealership), and various other auto-mechanically knowledgeable friends are all TOTALLY STUMPED…

ANY ideas from the audience???

[MisterTwo]

Complete guesses, but...

Have you tried resetting the ECU? Something could have gotten wonky after all the different conditions your O2 sensor was seeing.

Is O2 sensor #1 on one of the header down-tubes or past the collector? I know the NSX guys have lots of issues with the header styles that place the O2 sensor before the collector.

How do the spark plugs look?

Other than that, you could put the car back to stock to see if that resolves your issue. If it doesn't at least you will be able to troubleshoot with less variables.

I got my new OEM (NGK) O2 sensors here (www.sparkplugs.com) way cheaper than the dealer.

Good luck!

[GBL1]

How do you "re-set" the ECU...just pulling the correct fuse to re-set the check engine light? I have been doing that...too many times.

Yes, O2 #1 is prior to the cat...#2 is after the cat...just there to make sure that cat is doing it's job. #1 can affect air/fuel ratio mixture.

Spark plugs look fine.

I want to avoid having to un-do all the work, put it back to 100% stock, then turn around & re-do the work. It sounds like a lot of hassle & shouldn't be the culprit...all I did was add a header & exhaust.

Thanks for the link....

[MisterTwo]

How do you "re-set" the ECU...just pulling the correct fuse to re-set the check engine light? I have been doing that...too many times.


Yeah that's the one...

Sounds like a new O2 sensor is probably a good idea, but other than it probably needs to go back to the shop that did the maintenance. :(

[NAiL05]

First of all if you go to UTI you should have access to factory scan tools to monitor your fuel trims ask a teacher. From then on would I go on with your o2 sensor. you should be able to look at fuel trims short term and long term to make sure they are switching properly. Also what kind of o2 sensor was replaced...I hope you did not use a generic one (autozone. oreillys) because those are always crap especially on import motors from what I have seen. o2 sensors always buy OEM. I do not know why you are running an o2 sim (imo waste). if you still have the stock cat. The larger diameter wont effect anything. Only reason you run those is if you have the cat taken out on those cars.

[Fubar]

My guess is the MAF got something on it during the rain and has been sporadic ever sense. Check the connection first, if that doesn't work your can try to clean it but that may damage it so be prepared to replace if cleaning doesn't work.

My 2 cents.

[GBL1]

I had to bite the bullet & let the dealership figure it out.

They're telling me that it's the ignitor and/or coil inside the distributor, sooooo...I NEED a complete distributor...including the internal ignitor & coil. It needs to be a known working unit that will fit my 2000 base model.

If ANYONE has one or knows where I can get one (new or used), let me know.

I can come pick it up today...

...I just need to find one asap so I can get her back driving.

George
214.629.1299 cell
972.233.0888 office

[goofygrin]

If your primary o2 sensor is both sporadic and now in a cheater... ya need to replace it. The primary o2 sensor is the only want the ECU knows how much fuel to add to the car. Its likely dumping raw fuel into the cylinders, flooding the engine.

The ignitor/coil would appear to spark, but it's too wet/not vaporized and a tech can easily assume that it's just weak.

OBDII? Should have fuel trims with a scanner... are they maxed out?

[NAiL05]

My guess is the MAF got something on it during the rain and has been sporadic ever sense. Check the connection first, if that doesn't work your can try to clean it but that may damage it so be prepared to replace if cleaning doesn't work.

My 2 cents.

No MAF's in preludes.

[altiain]

Returned car to installation shop: they checked it over, said timing was dead spot on, but that two connectors underneath that control timing were plugged in, but not ‘snapped’ fully. Assumed it was just a loose connection. Car runs great now…except for exhaust leak and periodic check engine light coming on (assumed to be O2 sensor # 1).

Removed mid-pipe & determined that one stud was cross-threaded preventing a full, tight seal. Forced to drive car w/ open header for 2 miles during course of the repair…but did not “get on it” at all. Replaced stud & gasket…no more exhaust leak. Added an O2 ‘simulator’ (metal extender sleeve in between sensor & exhaust pipe) thinking that sensor was getting too much from now bigger header pipes.

Car runs & sounds GREAT now (nice deep tone hum to the exhaust) except for “occasional” (about 10% of the time) v-tec not kicking in…car just stutters & sputters at v-tec rev mark (5200 rpms). CEL now coming on regularly after 10-15 minutes of driving. Had code pulled…indicated “O2 sensor # 1: low voltage”. Likely needs to be by-passed or replaced now…

Your car is telling you exactly what it needs – a new primary O2 sensor. Fix the known problems first, then you can work on the unknowns. In my experience, fixing the known problems usually takes care of the unknowns as well.

You should never “fool” or bypass the primary O2 sensor. Like goofy pointed out, your car is using the reading from that sensor to adjust fuel. If it can’t get a good signal from the primary O2 sensor, god knows what sort of signal the ecu is sending to the injectors.

I'll even tell you how it happened (in the billiard room with the candlestick! Oh wait, wrong forum...). O2 sensor wires get extremely brittle over time due to the heat from the exhaust. One of the wires was damaged during the initial header install, and that connection has gotten worse and worse every time the connector is subjected to more heat and more vibration. Which is why you started out getting an intermittent check engine light, and now the car won't run at all.

[GBL1]

Picking up a new O2 sensor at lunch today! Going to install that, re-install the distributor...then try her out. If no go, I have a borrowed (supposedly) good dizzy to swap in to see if that solves the issue. If so, we're good to go (means I just need a new dizzy), if not, then we go after the coil. From there, I call a dealership mechanic buddy of mine that does side work (Man! ...I should have thought to call him before going to the dealership...!)

I "should" have it figured out by tonight or tomorrow. I'm just P.O.'ed that the dealership's charging me $99 for non-committal & inconclusive answers...all while trying to to sell me very expensive services along the way.

The reason I bite-the-bullet & pay the dealership is because I expect expert & authoritative answers...not tire-kicking, head scratching, & shoulder-shrugging.

[quikag]

You should listen to Iain as he was one of the founding members of NTPOG (North Texas Prelude Owners Group).

[GBL1]

I installed the new O2 sensor, it still ran rough...then someone asked if I reset the ECU. I had only reset the CEL by pulling the fuse....

I reset the ECU by disconnecting the battery for 15 minutes...and she runs like a dream again....and the "stealer-ship" was full of it...and trying to fill their pockets with my money. Grrrr!

At least the dealer service director waived the $99 since they weren't able to provide conclusive answers....

[bluejae]

I installed the new O2 sensor, it still ran rough...then someone asked if I reset the ECU. I had only reset the CEL by pulling the fuse....

I reset the ECU by disconnecting the battery for 15 minutes...and she runs like a dream again....and the "stealer-ship" was full of it...and trying to fill their pockets with my money. Grrrr!

At least the dealer service director waived the $99 since they weren't able to provide conclusive answers....

glad things got fixed for you