K87ZZ4

I think all of these symptoms may be related... I noticed my 87 was hunting for idle (between 500-700 RPM). It's worse with no load and smooths out pretty well under load (such as A/C on). I replaced the IAC, but the hunting for idle remains. And, since then, I've gotten a Code 45 (Rich Exhaust) a few times. The car seems to run fine, other than at idle.

I just took a road trip and the MPG was waaay off between what the dash shows and what I calculated. It was showing 33 and I calculated 22. On a long road trip, I usually get 26-27. If the ECM is seeing rich exhaust, it's probably trying to lean things out, right?

When it was 90+ degrees, over the weekend, I could smell fuel at the rear of the car. I figure this could be because the Evap (EECS) System might not be working quite right.

For a Code 45, the Haynes manual suggests checking the charcoal canister for the presence of fuel. I loosened the brackets that hold the canister, and it feels pretty light. I don't think I can open it. How do you check for the presence of fuel? If you find fuel, that's normal, right? It also suggests replacing the O2 sensor. Is that a likely culprit?

If it's running rich most all the time (or at least at idle), there's a chance I can burn out the cats (I have mini-cats), right?

Thanks for your input...

gerardvg

Check the fuel pressure regulator, if the diaphragm splits the engine will draw the fuel through the vacuum hose. This results in the engine sump filling with fuel.
Remove the vacuum hose and make sure it is dry, check the fuel pressure it should be around 38 psi.

Of course you may have to check the fuel hoses at the tank, you have to remove the lid assembly and the rubber boot. Run the engine and make sure the hoses are dry.

The charcoal canister breather hose needs to be higher than the charcoal canister or fuel can leak in certain circumstances.

Check the fuel injectors and below the fuel rail make sure there are no leaks.

Good luck

Cliff Harris

You might have a broken link in the fuel tank vapor line that goes to the charcoal canister. It is located in front of the left rear tire under the car. Two steel lines are joined together by a rubber hose about 2" long. This is what it looks like on my car:

K87ZZ4

Thanks for the replies. I pulled the canister out and checked all the hoses (I only removed the top vacuum hose) and everything looked fine (no kinked hoses, etc.)
The FPR vacuum hose is dry, too (I checked it a couple of times, including right after I shut the engine off)

Thanks for the pic, Cliff. I will check out that hose.

The Ck Engine (SES) light came on, again, yesterday after driving for 10 mins and just getting on the highway.

If the canister is being purged all the time, no harm done, right?

Does that likely point me at the O2 sensor, then? None of the fuel vapor stuff should effect idle runability, right?

I couple of weeks ago, I tried hooking up my cable and software (it's been a while), but can't get it to connect to even read codes. If I can get that working, I can check O2 counts.

65Z01

There ya go; verify cross-counts when warm and check BLMs & Int values.

K87ZZ4

I'm thinking the fuel smell/canister thing (since it's not full of fuel) is coincidental/red herring and I'm inclined to think the O2 sensor is working correctly and is telling me that engine is running rich, which also fits with the lower-than-expected fuel mileage. So, the question is: why?

According to the FSM, a code 45 is set when it's in closed loop and the O2 sensor records a high (> 0.7 V) reading for more than 50 seconds. The FSM lists lots of potential causes.

On page 6E3-B-7, there's a list of things to consider for rough, unstable idle. One of them is the A.I.R. system. It says "there should be no air to ports while in closed loop". A few years ago, when the car failed emissions (high Hydrocarbons (of 450; limit 220)) at idle, a shop said a component of the A.I.R. system wasn't working right (the diverter or switching valve, I think), but also said a replacement part was not available. Even though it failed emissions, at idle, it idled and ran fine. So, if the valve isn't working right and there IS air to the ports in closed loop, that means it's potentially injecting air into the exhaust, right? How would air injected into the exhaust cause a high hydrocarbon reading at idle?

xrav22

[QUOTE=K87ZZ4;1587501689]I'm thinking the fuel smell/canister thing (since it's not full of fuel) is coincidental/red herring and I'm inclined to think the O2 sensor is working correctly and is telling me that engine is running rich, which also fits with the lower-than-expected fuel mileage. So, the question is: why?

According to the FSM, a code 45 is set when it's in closed loop and the O2 sensor records a high (> 0.7 V) reading for more than 50 seconds. The FSM lists lots of potential causes.

On page 6E3-B-7, there's a list of things to consider for rough, unstable idle. One of them is the A.I.R. system. It says "there should be no air to ports while in closed loop". A few years ago, when the car failed emissions (high Hydrocarbons (of 450; limit 220)) at idle, a shop said a component of the A.I.R. system wasn't working right (the diverter or switching valve, I think), but also said a replacement part was not available. Even though it failed emissions, at idle, it idled and ran fine. So, if the valve isn't working right and there IS air to the ports in closed loop, that means it's potentially injecting air into the exhaust, right? How would air injected into the exhaust cause a high hydrocarbon reading at idle?[/QUOTE

My idle surge was fixed by changing a toasted o2 sensor.
It does have intervals so it needs to be changed every so often.
code 45 is running rich, precisely what the o2 sensor is there for.
It was worth a try for an oem Bosch for 20.00. Check the wire to it
can get broken easily.

K87ZZ4

Thanks... it's good to know what your experience was like. I'm not sure I've ever replaced the O2 sensor... I had the exhaust system replaced 5 years ago, it *might* have been done then. I'd rather not throw parts at the problem, but I also can't get my cable and software to work... and I wasted over an hour on that, already

K87ZZ4

If the ECM is sensing rich exhaust, it's going to lean out the fuel, right? That would explain why I'm seeing higher-than-usual mileage displayed on the dash by the ECM, but seems counter to the lower-than-usual fuel mileage I'm actually getting (when calculated manually). Would a leaky injector account for these symptoms?

I now seem to have an intermittent problem... because, yesterday, the car started idling smoothly, again. And the dash mileage is back down where it usually is. I still haven't been able to get my cable/software working, despite too much time spent trying

Red89'-L98

Any updates on your problem?

I got a code 45 yesterday and once a few months ago. I thought I may have smelt fuel (I have a lack for the sense of smell) and the idle was acting up a little bit like it couldn't decide between staying at 600 RPM's or 700 RPM's.

I am also getting worse MPG I was getting close to 350 or so depending on how I drove and now i'm around 250 at most.

My canister and all looks good also but I am no expert in that area and only "looked" at it. I have not checked the O2 sensor yet but will tonight or this weekend.

EDIT: I just remember also that last time I filled up my tank it was 1/4 full and when I opened the gas cap, there was a lot of of in-tank pressure which leads me to believe something in the canister system.

DannyBlake10

I know i had a fuel leak in the regulator. right where the two parts of its shell are put together and its folded over

Cliff Harris

The ECM sends the injector pulse width to the dash, which uses that info to calculate the mileage. If the ECM is narrowing the injector pulse width in an attempt to lean out the mixture then the dash will display higher than normal mileage.

Which cable and software are you using?

A lot of people use TunerPro because it's a good program and it's free. It's kinda difficult to get it to connect up to the car because of the arcane steps you have to go through...

K87ZZ4

Cliff, I was trying to use an AKM cable and Digimoto Lite or ScanMaster software on my old XP laptop, but it's just not working (and I've spent waaay too much time trying to make it work). So, I gave up and ordered an ALDL Bluetooth adapter cable, which should arrive tomorrow. I should be able to monitor using my phone, then. I *almost* just threw an O2 sensor at the problem to see if it would stick :-), but I really want to see what's going on with the O2 and the Block Learn and diagnose it (as I won't be surprised if it's NOT the O2).

Danny, I also checked the regulator by unplugging the vacuum line, but didn't see any fuel.

K87ZZ4

The Bluetooth adapter cable arrived today! I jumped right on it and installed the ALDLdroid software on my phone, but can't get it to work yet. I'm hopeful I will get a response from support tomorrow.

I was SO hoping I could get some data today and make progress toward getting this problem fixed :-(

Red89'-L98

I am curious to see how the bluetooth aldl device works.

I might be extremely interested in that if it works good.

I hope you get it working and get the problem figured out soon.

pcolt94

In addition, I would check out the charcoal canister, relay valves and related hoses for proper operation. They can be a major factor of smell and possible other related problems.

K87ZZ4

The ALDL Bluetooth adapter is working and I have the ALDLdroid software working on the phone now, too! So, I can now see real-time DATA on the my Android phone! It turns out I didn't have the right ADX file for the ECM on my 87. Once I got that, and used my laptop to move it to the ADX folder for ALDLdroid on my phone, I can read data! It turns out that you need to provide power to the ALDL Bluetooth adapter (they send you a wire you can add to your ALDL connector, but I discovered (by accident) that if I plug a (square) USB cable into the adapter, my laptop/or lighter plug can power the adapater... good enough for the time being without having to tap into a switched 12V source under the dash somewhere).

During a quick 1-min test, at idle (in open loop, of course), I was seeing BLM of 118 and O2 between 450 and 600. O2 cross-counts typically between 90 and 250. Base Pulse Correction of 128. Rich/Lean = Lean. It's been far too long since I had my head deep into this stuff, so I would appreciate any quick feedback on what this data indicates or point me to a source of a good overview.

Thanks much!

K87ZZ4

How, exactly, do you check for proper operation of the Evaporative Emissions Control System (EECS)? I pulled the canister out, and it wasn't full of fuel, so I guess that means IT is okay. Since it captures fuel vapors, it's hard to tell if it's working properly. The hoses on my system have been attached for over 25 years, they did NOT come off easily!

pcolt94

It sound like you went far enough. If there is no heavy gas smell, its probably OK. At least that's an area you can cross off.

Cliff Harris

The ECM increments the O2 cross count every time the O2 sensor goes from rich to lean or from lean to rich. The number should increase continuously while the engine is running in closed loop mode. It increments about every second or two and goes up to 255 and then wraps around to zero and starts over.