Problems with fuel supply.

[ZeroLux]

Hey guys, trying to figure out what is wrong with my 89 LX-i still, and I have a few new ideas. I'll give a basic description of what's going on.

I cannot take the car at high speeds for any prolonged amount of time. Let's say I hit the highway doing over 55mph, after about 3-4 miles the car starts getting hard to keep at speed. Pressing the gas pedal does not help much unless the transmission kicks down and that only happens momentarily before it goes back to higher gear. If I try to maintain speed for much longer after the engine starts to bog I typically wind up with what sounds like detonation chatter from the valves in the chamber, usually followed by dark colored smoke coming from the exhaust. If I leave the highway and sit idle for a minute or two at a red light everything sounds normal, when I set off from the light however I get more brief chatter and more smoke and very little power for a few seconds and then the car clears up and drives right.

I recently replaced the water pump and in the process of doing so disconnected by mistake a hose that was in my way that at the time I thought was the fuel supply line. Turns out from reading the FSM a while ago it looks like the return line. It's on the drivers' side of the fuel rail and was a larger rubber hose coming out of a regulator that pointed down. When I disconnected this, the fluid coming out of it wasnt clear. It had a milky white color to it. I thought this was fairly odd but being that the fuel system wasn't my focus at the time (my shredded water pump pulley and dead pump were) I let it go.

I recently checked the catalytic converter and it was clear so it's not the cause of losing power on the highway. I thought I might have been getting too much exhaust back pressure since it occasionally feels like my EGR valve is either opening at the wrong time, too often, or being forced open by another source.

I did some work to her last week and noticed that vacuum line #12 had a cut in it. The hose was located between the throttle body and the canister by the squidbox. I taped the line shut and used a ziptie around the tape to keep it closed before I can replace the line.

My gas mileage is also pretty bad right now, on a fill up this week I got slightly over 230 miles to the tank. Normally this would have been much higher. If the smoke coming out the back is dark would that usually mean there's too much gas or too much air being spent?

I am wondering if the problem could be related to any of the following:

* Bad fuel filter
* Bad Bypass Valve
* Something (condensation/water) entered the #12 line and has jammed it
* A sensor problem I have not found yet

The car has had this problem since I got it and I don't know what the previous owner had done to it over the years, so this problem is not new. This car also has had NO mods done to it beyond repairing various parts with OE or close to OE replacements.

Any information would be very helpful. This car is starting to drive me nuts with the way it runs.

Thanks!
Zero

EDIT: There are also no codes being thrown from the computer, I checked that a couple of days ago. I did reset it by pulling the clock fuse about a month ago when I did some other work to it though.

I have also done the following repairs to it in the last few months:
New alternator
New water pump
New dist cap
New dist rotor
New NGK plugs
New NGK wires
Two new O2 sensors installed
Seafoam via the brake booster line
Techron on a full tank of 89 grade gas

[bank2me]

EGR Valve maybe? I'd check it for sure man.

[2oodoor]

hate to say it but it sounds like a head gasket, mine did that exact thing one time and never overheated either. It was cutting up so bad one day on the way home from work, it would go up to 70 -80 mph but that is it. Pinging and carrying on, I stopped driving it, then when I tore it down I saw the gasket blown. How long has it been running like that, if it has been weeks then likely is not a head gasket or it would be overheating.

Other things to look in to would be distributor shaft and advance mechanisms condition. Fuel pressure regualtor, but did you say you had a carb or FI? You said return line so I assume FI. EGR would not slow you down that bad, those usually are problems for idle speeds.

[cygnus x-1]

By dark smoke you mean black? Like what you would see coming from an old diesel truck? That means it's burning too much fuel. Since you already replaced the O2 sensor I would guess maybe a sticky fuel injector or bad MAP sensor. More likely a sticky injector since a bad MAP sensor would probably trip a code. You can try running some fuel injection cleaner through and see if that helps. Otherwise get some extra injectors from a junkyard and try swapping them out one at a time.

C|

[ZeroLux]

Yeah I was thinking about hitting up the local pick-n-pull tomorrow to see what I can figure out part-wise on this thing. I don't think it's the head gasket though. Car has not overheated and has done this since I got it about 5 months ago. She's always run bad in some way shape or form and I'm still trying to hammer out the problems. I got most of the issues solved but this one persists. I've already run Techron in the tank and Seafoamed it by way of the manifold vacuum off the brake booster line. I was thinking the black smoke was a fuel issue too, which is what prompted me to change the O2's, but I have to wonder if it's getting enough air when it's running like that? The car overall seems to be running rich all the time. New air filter was installed after I got it and is routinely checked. From what I can tell- and I cant say all this for certain- the previous owner looks to have had some intake work done (completely replaced is what it looks like, or reman'd) not too long ago. New(ish) injectors, intake is nice and clean. I dont want to rip into the engine just yet especially how the engine itself mechanically sounds great. What other reasons would I be getting too much fuel/not enough air that I can try to diagnose this weekend?

Thanks a ton guys, the help is very appreciated.

Zero

[ZeroLux]

Fuel pressure regualtor, but did you say you had a carb or FI? You said return line so I assume FI. EGR would not slow you down that bad, those usually are problems for idle speeds.

Yeah it's injected, LX-i model A20A3 engine.

Zero

[ZeroLux]

Also I remember reading something a while back on another forum about the possibility of one of the two coolant temp sensors being in the chain of command to tell the PCM how to set the air/fuel mix- could this be part of the problem at all?

Zero

[Dr_Snooz]

I'll confess that I'm stumped. It really, really sounds to me like an exhaust restriction, possibly an intake restriction.

Random thoughts:

Did the Seafoam help at all?

I wonder if they buggered the intake installation somehow, put the wrong manifold on, stashed their crack pipes in there or whatever.

I'd look over the entire air supply/exhaust system looking for anything out of the ordinary. Look up the tailpipe, bang on the pipe, muffler, etc. Look for some kind of sound indicating a blockage. Pull off the air filter housing, look it over, look in the intake plenum as far as you can see, etc., etc., etc.

Not sure if you have the manual, but if you don't, get it and start testing any module that springs to mind. You're bound to find something bad. Start with your MAP sensor, atmospheric pressure sensor and speed sensors as they have the biggest impact on running performance. Please, please, please don't just replace random parts because they might be causing the problem. You'll be into big money fast and won't have anything to show for it. The manual has good diagnostics for everything.

The temp sensor usually causes a warm start problem, not a running problem.

Please keep us posted, I'd like to know what you learn.

Good luck!

[Oldblueaccord]

Unhook something and casue the computer to throw a code like the map sensor. I wonder if the ECM is not functioning properly.

Also is the car coming up to operating temp. making heat etc? The temp guage should be at least 1/4 of the way up.

EGR has little to do with how a car runs over all esp rich or lean.


wp

[ZeroLux]

Yeah the car reaches operating temp just fine. TBH- it drives like a car running rich, is the best way I can say it. No power, sluggish, difficult to drive really. I thought about the ECM too, and it has thrown codes before but only for the EGR valve and it does not say it all the time, maybe once a month if that many. I thought it was a plugged exhaust somewhere too but I have yet to find it. I DO get an odd pulse from the exhaust pipe though, feels like pop pop pop (x3) pause pop pop pop pop (x3) over and over again. It's not a misfire I checked for that too. It just seems like something is jammed somewhere. That's why I had the cat checked. Is there any way using trickery or anything to FORCE the car to run a certain mixture?

Thanks for the suggestions, I'll try to piss it off more in the morning and see if it barfs on me.

Zero

[cygnus x-1]

Every indication says it's getting too much fuel. I would check that coolant temp sensor for sure. That would definitely make it run rich.

C|

[Demon1024]

2x temp sensor---^
if you got white goo in your lines drain your tank and change both the filters
maybe plugged return line? as fun as it sounds you can blow into the hose and hear it in the tank to check take off the gas cap first tho

[ZeroLux]

Which of the two sensors is the one that dictates the fuel mix? There are two close to the throttle body on my intake, and if i remember right one has a green plug with two wires (passenger side) and the other has a yellow plug with two wires (drivers side). I checked the one with the green plug and did not find any problems but didn't take the other one out yet. I have the 995 page FSM for this car and it's been helpful but calls for tools and test harnesses that I don't have. Is there another way to test the MAP sensor without the test cable they talk about? As far as an airway constriction what would be a good way to test out the intake itself? If I am reading the FSM right the diagram for the intake looks like it has two chambers to it, on is open for the primary airflow and it looks like there's a vacuum actuated arm attached to the bypass valve that opens a second chamber for more airflow at higher speeds (?). I probably have that wrong or backwards but it's a start. What if that part is not opening the way it should? I am much more familiar with Neons than with Hondas so if this sort of thing had happened to my Dodge I would typically know right where to look. I am trying to apply what I know of it to this car but the design is completely different in it's operation.

Zero

[Oldblueaccord]

https://www.3geez.com/forum/showthread.php?t=60400

TW sensor. but the pictures are down that needs to be updated.

I think the MAP is 0-5 volts. Most of the other sensors read a resistance based on temps.

EGR code does seem to reset itself I have found. It prolly is bad but over all should not make a big differance unless it makes the EM run in "limp home" mode.

Only other thing might be to look at the ECM. some people have had a water leak lead to corrosion on the case and ground giving some wierd errors.


The pop pop at idle is normal on my car as well sounds like a misfire from the back end but other wise normal condition. Changing the coil may help this. Remember there is no tail pipe on the muffler so cold air runs into the muffler.

wp

[ZeroLux]

OK, I read the link oldblue posted above and it confirmed what I had been suspecting as being part of the problem before. Now, here's my question. I tried this tonight. I got in the car, drove a bit till it was at operating temperature and stopped at a gas station to try out the paper clip trick. Got it installed looked good, got in and started up the car. It instantly flagged the check engine light. So as opposed to trying to drive it that way and potentially running the car lean instead of rich (I prefer the lesser of the two evils and will stick with rich for the moment), I turned the car back off and removed the jumper from the plug for the TW sensor. Plugged it back into the sensor as normal and restarted the car with no CEL on the dash. I did not get the chance to poll the codes out of the ECM yet but if it's the type to retain problem codes I'm sure it will be there in the morning too. Was this an expected reaction? The post didn't go too far into the specifics of that part, just suggested the jumpering (or at least I think I interpereted it right and pulled the plug socket off the TW sensor and jumped the two wires inside with a properly fitting metal piece) to bypass the TW sensor's incorrect reading. Any thoughts?

You guys have been great through this, If this were the Neons forums I'm used to, there would have been nothing but flaming and sarcasm from a bunch of judgmental pricks.

Thanks a ton again!

Zero

[Dr_Snooz]

The MAP sensor diagnostic procedure begins on p. 12-22 of your manual. You can do the procedure up to the test harness portion and see if you learn anything from that. Looking at that test harness, it looks like it just keeps the wires all connected so you can measure voltages passing through the circuit. Up until this point, you've just been measuring potential voltages. You are ensuring that power is available, but not that it's flowing. Anyway, you're measuring voltages between color coded wires. The schematics at the back of the manual will tell you where those wires go. If you figure that out, you can probably figure out what the test harness is testing and how to get around buying one.

Having said that, I'm reluctant to point to most of these sensors because they will give you a CEL if they go bad. I've never heard of a 3g MAP sensor going bad. Nevertheless, testing them is free, so you may as well.

My money is still on a restriction of some kind. Right now, I'm trying to figure out why you have a new intake manifold. Replacing the intake on a 3g is a tremendous amount of work. You'd need a real good reason to do that and I'm at a loss to understand it. You know the car and the previous owner better than I do, what do you think was going on? That could tell you a lot right there.

As for the flaming, our cars are awesome and we know it. No need to flame to make ourselves feel better.

Again, please keep us posted as to the outcome. Thanks!

[ZeroLux]

No man, thank you. I thought a MAP sensor going bad sounded a bit uncommon to me as well, since I've worked with other cars using the same thing and they are solid state and I have yet to see one ever go bad (the Neon has one). I am leaning quite a bit towards that TW sensor at the moment but it seems finding one isn't going to be easy. I went to the boneyard today and scavenged but came up with nothing- interestingly, all the TW sensors on ALL the similar model Honda's I found out there were- uhm- gone.

I'll tell you what I would like to do though, let me take some pictures early in the AM of the way my engine looks. Everyone I have spoken to about the car that knows a bit about Honda's in general always comment on the cleanliness of the intake, alternator, and water pump. All of which are recent. From what I was told, the intake was rebuilt a couple of years ago but I am not certain as to why.

Truth be told, I got the car from a buddy of mine locally whom only had it for about eight months before buying an '08 Civic SI 6spd (is there an emoticon for drools?) and HE in turn got it from the ORIGINAL owner who bought it back in '89. The original owner is the one that had the intake rebuilt, he was a client of my friend's at the shop he worked at and my friend was relatively familiar with the history of the car. Unfortunately he didn't know the specifics behind the intake change. I do have two small leaks on both driver's side injectors but it's due to the O rings and nothing more so there's a bit of stuff around them. Maybe from the pictures someone might get a better idea of what I am looking at on my end.

To be fair about the Neon forum, I <3 my Dodge. Always have. She will run again one day, but that's another story. Unfortunately some of the members of that place have a bit of a god complex when it comes to Mopar and as such developed quite the ego towards 'lesser' people in their opinions.

Zero

[ZeroLux]

So I went this morning and warmed up the car to test out the TW sensor. According to the FSM I downloaded on page 12-26/27 the proper ohm range for a working sensor is between 200 and 400 ohms resistance. I checked the voltage coming out of the socket in the harness for the 5v it needed and it was correct so my wiring appears to be fine. However, I did find that at operational temp the sensor was only giving a value of just under 150 ohms resistance. This seems to function by way of lowering the voltage from the 5v source in the harness to the ECM unit to tell the car that it's warmed up. If the resistance was only 150 ohms I am guessing it would be feeding too much voltage back to the ECM and keeping the car in a rich status. Now, when I tried the paper clip trick I instantly got a CEL warning on the dash. After thinking on it I realize that the metal jumper used as a temporary fix would in fact be providing NO ohms resistance (or extremely little at least) thus making the car think it was running COLD. Now, if I were to go to RadioShack and find a 1/4 watt resistor with a value between 200 and 400 ohms and jump THAT into the socket instead of a paper clip I would imagine the voltage drop would properly tell the car that the engine is warm. This won't be a permanent solution since I would think that starting the car with it in place would make the ECM think it's already warm when in fact it's not and not feed enough fuel into the chambers.

Thoughts anyone?

Zero

[Dr_Snooz]

I'm assuming you had the car at operating temp, right? If so, your sensor is bad.

I wouldn't try to jury-rig it. I got mine from Napa. If they can't help you, hit the dealer.

[ZeroLux]

I'll use it as a temporary measure. I put in a 330 ohm 1/4 watt resistor and taped it down with electrical tape when the car was at operating temp. Seemed to help quite a bit but I know it's not a great idea to leave it there. When the car is cold I'll be reconnecting the old sensor then if it starts aggravating me again I'll use the resistor trick again. NAPA has this sensor available? Everywhere I've checked locally so far are clueless to it's existence and just want to sell me the other sensor. I never remember NAPA is around though, I'll have to give them a call. Thanks for the info!

Zero

[ZeroLux]

Hey would you happen to know the part number for the NAPA one? I checked their website and I see listings for about 6 or 7 sensors all claiming to be the same thing.

Zero

[cygnus x-1]

Sounds like you're on the right track. One trick with NAPAs website though, use the PartsPro SE catalog link and search that way. The rest of the site is just a PITA.

The resistor trick is not so bad really. If you wanted to get really fancy you could get a couple different value resistors and a switch. Then you have one for cold and one for warm. Ok, maybe that's just silly.

One other thing that occurred to me, are the secondary intake ports actually opening up? If they aren't it would cause an intake restriction when you get on the gas. I'm not all that familiar with that intake but there should be an actuator on the side somewhere.

C|

[ZeroLux]

No, not silly, I was considering setting up a potentiometer to do on the fly fuel control actually :P Switched between stock sensor (once I replace it, NAPA has it but I am broke at the moment) and the variable resistor tuned to provide 200-400 ohms. And I was wondering about the secondary intake ports too, the lever on the driver's side that actuates it by vacuum moves freely but when I move it by hand with the engine off, I get a 'squishy' sound.

As soon as I figure out where the heck I put my vacuum gauge I'll give it a test and see what happens. It seems as if more than one problem is currently effecting the car so I'm just narrowing my way down through it all little by little.

Oh yeah- starting the car this morning forgetting I had the resistor installed... bad idea WHIR WHIR WHIR PUTT stop... "OOPS! stupid me" reconnected the sensor and it fired right up.

Thanks for the direction and support guys!

Zero

[1987AccordLx-i]

Sounds like you're on the right track. One trick with NAPAs website though, use the PartsPro SE catalog link and search that way. The rest of the site is just a PITA.

The resistor trick is not so bad really. If you wanted to get really fancy you could get a couple different value resistors and a switch. Then you have one for cold and one for warm. Ok, maybe that's just silly.

One other thing that occurred to me, are the secondary intake ports actually opening up? If they aren't it would cause an intake restriction when you get on the gas. I'm not all that familiar with that intake but there should be an actuator on the side somewhere.

C|

the only way i see him checking the secondaries is under load.. i have no clue if they open up in neutral.. but sticky secondaries sounds like something that would mess with a/f readings

EDIT: zero beat me by a few mins haha.. so its not secondaries?

[Oldblueaccord]

The secondaries only come on after 5500 rpm but by the book they can be test in neutral. Open or close shouls make little differance.

The paperclip deal i never understood either I dont see how that would work but my is got the right resistance if its a small one ?

I have a pot I was going to setup with my wideband o2 sensor but I just am getting around to it this month.


wp