Questions about PGM-FI system.

[ZeroLux]

Been having continued problems with my 89 Accord LX-i lately, had a few thoughts. I understand that the fuel management system is fairly primitive and is prone to fault fairly often. It seems like at anything but WOT my car runs rich (fuel economy sucks, bogs like hell in a similar way to another car I own does when an O2 sensor goes bad) and I am starting to think it's an electrical problem with the ECU. If I were to remove one or BOTH of my O2 sensors what kind of an effect would it have on the car? I am thinking one or both are fouled and causing the car to think it's running lean all the time and dumping more fuel than needed. Ideally I'd like to just delete the whole O2/EGR system flat out since it's not doing much that I can tell (ok sure, partially emmissions but i dont see how spitting gas into the atmosphere and clogging my cat is helpful either). If I unplug both would the car totally go to hell or is there a chance it will right itself for a bit? Also, as opposed to removing both (since they are side-by-side) if I were to install ONE new one and leave the other disconnected to plug the hole in the downpipe would the car run ok that way too? Something's gotta give here, the car just does not drive right and it's becoming a bigger annoyance every day. Any info about the fuel control system would be greatly appreciated.

ZeroLux

[LX-incredible]

I would install the two if that was the problem... Could also be the TW sensor. With those miles I would replace the O2 and TW sensors, as they're usually on their way out by now. Unplugging sensors is never a long term solution.

[ZeroLux]

I'm new to Honda's... TW sensor? Speaka da engrish pls. Seems like this car is totally different from what I am familiar with and I'm finding it hard to get used to how it's setup. I also think I have a vacuum leak somewhere but that's a story for another weekend. So temporarily won't have any drastic affects? Would it natively run rich or lean without the O2's plugged in?

ZeroLux

[ZeroLux]

Ah. Wait, TW sensor = Coolant Temp Sensor, no? It seems I have two of those as well. Temp has never been a problem- think they need replacing?

ZeroLux

[w261w261]

<< I understand that the fuel management system is fairly primitive and is prone to fault fairly often >>

I've had my '89 f.i. for 7 years and 86k->210k miles, and it has run consistently good. Once you get yours set up correctly it should serve you in the same way. You could call an AK-47 "fairly primitive" too, but there's a reason they've been the choice of most of the world for the past 50 years or so.

If you're mechanically inclined, go through the car methodically. You'll get the answer. There's lots of experts here who can help, and by using the search function, you can get lots of info yourself. 240k is not a whole lot of miles by 3G standards, but it sounds like your car needs some "catch-up" attention.

[ZeroLux]

Yeah it seems the previous (original) owner of it was a bit harsh to it. I've been trying to doctor her back to good health for the last few months but time and money have been tight. BTW- she just rolled over 241k on the way back from the store tonight (late night soda run). I expect many more miles out of her and tbh the engine sounds mechanically fine, nothing out of the ordinary there, I just think some of the supporting hardware externally could use a bit of a refresh.

ZeroLux

[LX-incredible]

Ah. Wait, TW sensor = Coolant Temp Sensor, no? It seems I have two of those as well. Temp has never been a problem- think they need replacing?

ZeroLux
It's the one with smaller 2 pin connector. The larger green connector is for the aux fan and the single pin is for the temp gauge. What you see on the temp gauge might not be what the sensor is feeding the ecu.

[w261w261]

My experience with the TW sensor (less than 20 bucks at Honda, I believe), was that when it was failing, it messed up the low RPM performance mostly (I put a new one in in the parking lot of the dealer....that's how bad the starting had gotten). I'd replace it now, on general principles if nothing else.

This place sells Honda parts at 25% off:

http://www.hondaautomotiveparts.com/auto/jsp/mws/catdisplay.jsp

I wrote message #20 in this thread about some common things to do to our cars to make them more reliable:

http://www.3geez.com/forum/showthread.php?t=66425

If you haven't already, throw some Techron in the gas. Good luck.

[Oldblueaccord]

Been having continued problems with my 89 Accord LX-i lately, had a few thoughts. I understand that the fuel management system is fairly primitive and is prone to fault fairly often. It seems like at anything but WOT my car runs rich (fuel economy sucks, bogs like hell in a similar way to another car I own does when an O2 sensor goes bad) and I am starting to think it's an electrical problem with the ECU. If I were to remove one or BOTH of my O2 sensors what kind of an effect would it have on the car? I am thinking one or both are fouled and causing the car to think it's running lean all the time and dumping more fuel than needed. Ideally I'd like to just delete the whole O2/EGR system flat out since it's not doing much that I can tell (ok sure, partially emmissions but i dont see how spitting gas into the atmosphere and clogging my cat is helpful either). If I unplug both would the car totally go to hell or is there a chance it will right itself for a bit? Also, as opposed to removing both (since they are side-by-side) if I were to install ONE new one and leave the other disconnected to plug the hole in the downpipe would the car run ok that way too? Something's gotta give here, the car just does not drive right and it's becoming a bigger annoyance every day. Any info about the fuel control system would be greatly appreciated.

ZeroLux


Its a speed/density system text book. I don't think its prone to failure at all.

Check the codes and see whats up from there. I dont think unplugging the O2 sensors will help it run better and certainly not any leaner.

wp

[Dr_Snooz]

In most cases, if you have an unplugged/failed sensor, the ECU will revert to a default map from the factory and give you a check engine light. Techron is always a good place to start for any amorphous poor running issues that don't give you a check engine light. You might also check those O2 sensors after the Techron treatment. As a general rule, you should avoid ghetto fixes. It just degrades the car and makes you sad that you now own an official POS.

[ZeroLux]

I figure for about $17 a pop replacing the O2 sensors is no biggie. It certainly beats the $70 to $90 from my old Neon whenever they went bad. How difficult is it to install a Air to Fuel Ratio sensor in this car? Could that take the place of one of my O2 sensors so I can at least see if it's going out of whack sometimes? I have not had my CEL come on in relation to this issue that I am aware of, thought occasionally (once a month maybe) it comes on giving an error code for the EGR valve. If I turn the car off and then back on, it typically goes away and stays gone. Not sure what the source of the issue is but I'll get to that eventually.

I'll pick up a bottle of Techron tonight and see how things go. Thanks for the suggestions guys.

ZeroLux

[ZeroLux]

Oh, and yes, I am aware the EGR is related to the emissions/fuel but like I said the problem does not happen very often.

[LX-incredible]

These cars will not run properly on a single O2 sensor. If you wish to run a single sensor convert to obd1. You will only get a CEL for sensors when they outright fail or connection is lost. The problem is usually not in loss of connection, but in a skewed reading from the sensor, (giving a 80º instead of 160º) causing the ECU to dump extra fuel for the 80º condition.

[lostforawhile]

I figure for about $17 a pop replacing the O2 sensors is no biggie. It certainly beats the $70 to $90 from my old Neon whenever they went bad. How difficult is it to install a Air to Fuel Ratio sensor in this car? Could that take the place of one of my O2 sensors so I can at least see if it's going out of whack sometimes? I have not had my CEL come on in relation to this issue that I am aware of, thought occasionally (once a month maybe) it comes on giving an error code for the EGR valve. If I turn the car off and then back on, it typically goes away and stays gone. Not sure what the source of the issue is but I'll get to that eventually.

I'll pick up a bottle of Techron tonight and see how things go. Thanks for the suggestions guys.

ZeroLuxa lot of airfuel ratio gauges will let you use the existing sensor. but the narrow bands of the factory 02 sensors won't tell you much. you need to spend the money on a wideband and wideband sensor if you really want one. the little flashing cheap ones aren't that accurate. as far as mounting one,you weld an o2 sensor bung in the down pipe somewhere.

[LX-incredible]

The EGR should only open at cruising speeds. My guess is you're only getting this on freeway trips? There is a lift sensor on top of the valve which checks if the valve is opening when the ECU activates the EGR solenoid. It could be the solenoid or the tubing, but more than likely it's carbon buildup in the valve itself. There's a thread about cleaning the EGR somewhere on here.

[ZeroLux]

Freeway... I wish. No, my car is still too moody to take on any road higher than 55mph for any more than about 5-10 minutes. No, I am not joking. But being that I've been outside all morning tinkering with it and replacing my front brakes I did a little investigating. Seems my O2 sensors are hosed pretty bad. Time for new ones. That could be 95% of my running issues with this car. At least that's what I'm hoping.

ZeroLux

[lostforawhile]

if it's been abused time to seafoam it too,

[ZeroLux]

Seafoamed it already about a month ago, just bought some Techron to put in tonight as well as two new universal O2 sensors to swap out and see what happens. List of things done so far:

New NGK plugs
New NGK wires
New Dist Cap and Rotor
Seafoamed
New Alternator

Still need to adjust my valves. Still need to check my compression. Prolly wind up doing an oil change this weekend too, a little early but after a recent experience I had with the car blowing white smoke (not burned oil, smelled more like gas) like crazy one night after jumping my buddy's RX-7 off of my Accord I'm a little concerned that some of it made it's way into the lower case. Any idea what could cause that (my thought was electrical overload from his battery being rated to 700 something amps and mine only being to 540 amps I think, at any rate it stopped after a few hours). We left the cables attached between the cars for a few minutes to be sure his RC would not cut off after the jump, might have back fed into my car?

ZeroLux

[ZeroLux]

Amazing what two new O2 sensors can do. Seems most of the hesitation, bad idle, and poor operating conditions at low sustained and regular road speeds are gone. Have not been able to test it 100% yet but I've got some driving to do tonight so I guess I'll see.

ZeroLux

[Oldblueaccord]

running rich you may have poisoned the catalytic converter also.


wp

[ZeroLux]

What would some symptoms of that be if that had happened? The car is running *better* but not *perfect* at the moment. It still seems a little moody on acceleration. I tossed in the Techron and filled it up with 89 octane earlier tonight. The plugs helped more than I thought they would. Seems most of the problems I was running into was directly related to the over-rich mixture. Hard shifting, wasn't able to coast at any speed without the engine dogging down (almost felt like engine braking), sporadic idle, just to name a few.

ZeroLux

[cygnus x-1]

Since you're getting a sporadic EGR code there is something going on with it. If it's sticking occasionally it would definitely cause seemingly random issues with light acceleration and cruising.

I think poisoning the converter would just make it fail emissions. And the exhaust would likely smell bad.

C|

[ZeroLux]

Luckily in North Carolina all cars that don't meet OBD-II compliance (pre-1996) no longer have to meet emissions on inspection. They dont even check for it anymore, the old sniffer machines are all gone.

ZeroLux