TCCoA Forums banner

1 - 20 of 41 Posts

·
Registered
Joined
·
65 Posts
Discussion Starter #1
Hey guys, new to the forum... well, I've been reading around and joined when I bought this car. I think my thread from yesterday got swallowed in the server change. I know redundant threads are not the best way to make a first impression around here so hopefully I've searched enough that this won't be totally redundant.

Recently bought a 94 LX V8 car, 125K, zero rust $750. Needs a little work, but motor pulls strong, no smoke, trans is strong. Really a nice car for what I paid. It has one annoying little problem I have yet to solve.

I drove it home with it wanting to die at tip-in (off-idle, not sure what you call it). Check engine light was on and it idled fast, 1200 or so in Park, around 1000 in gear. Doesn't start fast, rolls over a time or two before it lights off. Otherwise, runs great.

A friend pulled the codes for me... P0174, P0171, P0102, which are banks 1 & 2 lean and improbable MAF reading, if I'm not mistaken. Forum search number one led me to believe either vacuum leak or dirty/faulty MAF.

I checked for a vacuum leak... nothing obvious, so I decided to clean the MAF. Used the "MAF cleaner" in the aerosol can from Advance; I'm pretty sure I paid extra markup for relabeled contact cleaner, but at least I got the "right" stuff for the job... Reinstalled MAF, Disconnected/Reconnected battery to clear codes, although apparently based on my second forum search there is a fuse under the hood you can pull to do that... Anyway, started the car, no check engine light. :) Idle a little high, but calmed down to 800 or so after a couple blips of the throttle. :) Put the car in gear, idles right at 750. :) Pushed on the gas, and the car died. :mad:

I cranked it a few more times and repeated this trying to get it to throw a code... so far nothing. Just the symptom.

Based on the forum searches I've done (and I did several before starting this thread, although there is a similar thread close by it hasn't been fleshed out much yet and I know ppl get mad when you jack their thread) it seems like one of the following is possible:

1) Non-obvious vacuum leak upstream of manifold and downstream of MAF (no lean code yet but I don't know how long it has to go lean before it's thrown)

2) Bad IAC (this apparently is common once these cars start getting long in the tooth and can cause all kinds of crazy problems?)

3) Bad TPS

4) Needs plugs, wires, fuel filter, etc (haven't gotten around to this yet but it's high on the to do list)

5) EGR clogged possibly?

6) Bad gas (not much gas in it, probably sat for a while before I bought it. I hate E10; draws moisture and varnishes too fast)

How would you guys go about troubleshooting this one?

Thanks for your time,

Charlie
 

·
Super Moderator
Joined
·
11,961 Posts
first fill up on gas with a whole bottle of seafoam in the gas tank....then maintain anything and everything you can all at once, and post up exact what you maintained and how you did so...then you can go from there

FWIW, i'll put money on vacuum leak as one of your issues
 

·
Registered
Joined
·
65 Posts
Discussion Starter #3
Thanks Maestro!

Will commence with tuneup blitz and report back. Probably first things I will tackle will be plugs, fuel filter, and PCV. Will probably hit a couple of vacuum lines for good measure while I'm there. I'll probably also drain the tank when I do the fuel filter just to try and eliminate one possible issue. Bad gas is also cheaper than Roundup!

I changed the air filter when I did the MAF. Just used a Fram paper filter so no K&N oil yuck.

Right now I have the car off the ground replacing front UCA's, LCA's, strut rod bushings on both LCA end and on frame end, KYB struts and switching to Vogtland -1.6" springs. One stop at SCP.

First time I've ever loaded my credit card to the limit in one purchase!
 

·
Registered
Joined
·
1,170 Posts
A hard code on a MAF could mean its beyond repair you need a new one. I would like to see some live airflow readings with a scan tool. Maybe disconnect the maf and see if there are changes. Bad MAFs create hesitation on acceleration.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #5
Thanks for the input, tbirdguy!

I'll have to see if my friends' scanner has that capability. I know it can read codes, not sure on the sensor data. I think it's smart enough to do that but not 100%. I know he paid pretty good money (>$100) for it so it's a good possibility it does.

It's one more thing to check, anyway. The code has not resurfaced since I cleaned the MAF, but I haven't driven it much either.

Right now it has the nose in the air getting its front end gone through; there's a good 1/8" of play in the upper ball joints!:eek: One of the pitfalls of starting with a $750 car I suppose! As soon as the car is safe to drive it's on!

Totally unrelated but if you buy a Bird for $750, you can bet it has wheel locks and no key. And no jack. And no radio, but I digress. The "Lug Out" tool from Craftsman does work, but you have to use the 6-pointed side of the biggest socket and drive it on good with a BFH and use a breaker bar, not an impact, to break it loose. Basically, jettison the instructions that come with it because the tool I'm pretty sure is made for the spline-drive wheel locks and not the ones where the outside is smooth and round like the factory Ford ones. The first wheel lock took me an hour; the second took me 30 seconds!
 

·
Registered
Joined
·
65 Posts
Discussion Starter #6
Incidentally, I have a DMM and I was wondering if there's a "bench test" procedure for the MAF?
 

·
Registered
Joined
·
1,170 Posts
To set a code you generally need three drive cycles. Here is more info on testing a MAF:

http://www.stangnet.com/mustang-forums/780366-anyone-have-specs-stock-maf-93-l-x.html

With a scan tool or DMM figure a .7 ish voltage at idle, and it should rise smoothly from there as you open the throttle(an analog multimeter is helpful too to see the trends). It should also respond to a sudden throttle "goose" with a fast rise/fall time(skinny mountain peak on a graph). We call this a delta function in engineering. If it takes too long to respond or fall its bad. You can try cleaning it again but chances are its time to retire it.

Finally if you have a good scan tool(Ford Specific) there is a BARO parameter which correlates MAF readings to Barometric Pressure (like you see on the weather forecast). This can tell you right away if its bad. The parameter is measured in Hz for some reason, but can be easily converted to mmHg. A healthy MAF will read 159 Hz (29.91 in. Hg) give or take 5Hz at sea level. In Denver @ 5000' it may read 144 Hz (24.88 in.Hg). The baro parm resets every time you do three near wide open throttle actions. A healthy maf will actually work as an altimeter, I've tried it in the mountains and its pretty accurate.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #8
Thanks again, tbirdguy!

I have an analog MM somewhere. I'm pretty sure the scantool my friend has is just one of those Actron units they sell at the parts store, so I don't know if it will give me the MAF raw data.

I figured there was a way to test the meter using a DMM but I wasn't sure if I wanted to measure resistance or voltage and what values I would be looking for.

It is interesting that the reading is in Hz. I thought it returned a voltage to the computer. I guess it calculates flowrate based on the frequency of the element's vibration?

I too am an engineer, although I do HVAC design. I'm basically familiar with how air flow meters work but I'm no expert by any means.

I'll perform these tests and see what I come up with.
 

·
Registered
Joined
·
1,170 Posts
Thanks again, tbirdguy!

I have an analog MM somewhere. I'm pretty sure the scantool my friend has is just one of those Actron units they sell at the parts store, so I don't know if it will give me the MAF raw data.

I figured there was a way to test the meter using a DMM but I wasn't sure if I wanted to measure resistance or voltage and what values I would be looking for.

It is interesting that the reading is in Hz. I thought it returned a voltage to the computer. I guess it calculates flowrate based on the frequency of the element's vibration?

I too am an engineer, although I do HVAC design. I'm basically familiar with how air flow meters work but I'm no expert by any means.

I'll perform these tests and see what I come up with.

No, the Hz reading is actually calculated by the PCM, because the old MAP (manifold absolute pressure) sensors would generate a square waveform with a frequency corresponding to pressure. The MAF sensor generates a voltage. The part you clean is heated to a high temperature, and the trick is to maintain that temperature as the air flows across it. The amount of current is then proportional to the mass of laminar cool air flowing across the sensor. When you clean the sensor you are essentially removing the insulation (dirt) layer that builds up and skews the readings.

If the scan tool can read OBDII data you should be able to see air flow data. Also make sure the air and coolant temp sensors are reading properly.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #10
OK, that's how I thought they worked, but since I learned basically everything I know about EFI by reading Car Craft, I wasn't about to argue.

It is interesting that they convert a voltage (VDC) generated based on airflow (CFM) to a frequency(Hz) to emulate manifold pressure(inHg). I'm assuming it's so they can use the same algorithms as the speed density systems, but still have a system that reacts better to changes in operating conditions?

Anyway, hopefully I'll be able to test it over the weekend and see what I get.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #11
Holy Crap, There's a lot of hidden vacuum lines on this car...

Just took the violin case off to get to the spark plugs, and holy crap. I had read about the rubber tee to the passengers' side of the TB, and had I not read about it on here I'd have never found it. the S.O.B. came off in three pieces!!! Not to mention several other little chunks of vacuum line that disintegrated when I removed them.

As far as replacing that thing goes, am I better off trying to find a Ford part that's an exact replacement or going to Auto Zoo and getting a plastic tee and using bits of vacuum hose to piece it back together? Or perhaps will I find that exact part or a reasonable facsimile thereof at the Auto Zoo?

Maestro, you were dead on with the vacuum lines. I can't say for sure yet if that was THE problem, but it was sure as hell A problem.

When I get the front suspension back together I'll get the plugs changed and we'll see what's up.

Thanks for the assistance guys!
 

·
Registered
Joined
·
65 Posts
Discussion Starter #12
Just took the violin case off to get to the spark plugs, and holy crap. I had read about the rubber tee to the passengers' side of the TB, and had I not read about it on here I'd have never found it. the S.O.B. came off in three pieces!!! Not to mention several other little chunks of vacuum line that disintegrated when I removed them.

As far as replacing that thing goes, am I better off trying to find a Ford part that's an exact replacement or going to Auto Zoo and getting a plastic tee and using bits of vacuum hose to piece it back together? Or perhaps will I find that exact part or a reasonable facsimile thereof at the Auto Zoo?

Maestro, you were dead on with the vacuum lines. I can't say for sure yet if that was THE problem, but it was sure as hell A problem.

When I get the front suspension back together I'll get the plugs changed and we'll see what's up.

Thanks for the assistance guys!
Picking up new Dorman tee from Advance today.

Hoping to get some time in with the Bird this weekend and hopefully get it all back together.

Found a hood with good paint (well, salvageable paint) that matches the car for $40 at the U-Pull-It yesterday; gonna pull that tomorrow. Hood I bought the car with is light green, rest of the car is dark red...:gapteeth: Tree limbs suck.

Other than the $1000 I had to put into the suspension out of the gate, I really don't have a lot of cheese tied up in this thing...:D
 

·
Registered
Joined
·
65 Posts
Discussion Starter #13
Dirty Bird Update

New Hood ON. Aligning those is harder than it looks. Car is now all one color! I was afraid that the cars from two different model years (donor car was a 95) might have a slight difference in color but they seem to match perfectly!! :headbang:

All vacuum leaks I can find are fixed. PCV is new.

Plugs and wires (Autolite Platinum 0.054"/Autolite) have been replaced. Plugs looked fine, other than being lean, which we expected from trouble code and massive vacuum leaks. Previous plugs/wires were Motorcraft, so either somebody cared about the car or REALLY didn't care about the car! Based on the general condition of the old parts when I removed them I doubt they're the originals.

Driver's side front suspension is done. Pass. side front suspension is still in pieces. Still have LCA, strut rod bushings and swaybar endlink to install. Coilover is assembled and waiting to go in car.

While I have it in the air I'm gonna change the oil and fuel filter also. Hopefully it rolls this weekend.
 

·
Premium Member
Joined
·
2,545 Posts
Man.. talk about a freakin Restoration project haha. It sounds like you are really taking this one on Wide Open Throttle. GL man. I'm hoping to be back in mine in a month running like a champ.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #15
Man.. talk about a freakin Restoration project haha. It sounds like you are really taking this one on Wide Open Throttle. GL man. I'm hoping to be back in mine in a month running like a champ.
I don't go off half-cocked. For me to be comfortable doing with this car what I bought it for it has to be right... if for no other reason than the fact that it's a hour drive from my house to the airport where our local SCCA chapter autocrosses. That means powertrain and suspension have to at least be healthy if not totally dialed in.

The fact that I bought the car from a salvage yard is also no excuse for it to look like I bought it from a salvage yard, either. :D
 

·
Registered
Joined
·
65 Posts
Discussion Starter #16
OK, Official Dirtybird Update:

Car is now lowered, and back on its wheels. Toe'd out like a mofo but haven't been to tire shop yet for alignment and tires. Looks tough though. :D

Took it for a spin around the barn lot... Still has the tip-in problem, although it seems to be less severe. Here is a list of repairs I have made to date:

1) Cleaned MAF
2) Air Filter
3) Replaced every vacuum line I could find that was rotten or otherwise failed
4) PCV valve
5) Plugs and Wires

It seems like the IAC is hunting around for the right idle setting (surges a little bit when I put it in gear going from reverse to drive).

I also noticed that when the engine is OFF that the throttle cable appears to be slack. Is this normal?

Thanks again guys!
 

·
Super Moderator
Joined
·
11,961 Posts
It seems like the IAC is hunting around for the right idle setting (surges a little bit when I put it in gear going from reverse to drive).
if you've already reset the pcm, and this still happens, then this is indicative of a vacuum leak....been there, done that......after a pcm reset, the car should drive normally with no idle hunting what so ever IF there are no vacuum leaks (this I can attest to when I fixed a vacuum leak---i was shocked that the computer required absolutely no relearning, because the rest of the engine/engine parts were in top shape)....the computer code in the pcm reflects reality so well that no adaptation is necessary IF everything on the engine including sensors/actuators are working correctly
 

·
Registered
Joined
·
65 Posts
Discussion Starter #18
Dirtybird Update

OK, weekly Dirtybird update.

Checked IAC by disconnecting plug while engine running... engine died immediately. If I recall correctly from reading other threads, this means IAC is working correctly.

With engine idling, I sprayed ether around the intake ports at the cylinder head mating surface. No surges, so I'm fairly convinced there isn't a manifold gasket vacuum leak.

I reset the PCM and took it for another spin around the barn lot. Problem persists. Idle drops coming out of Park and it almost dies. Tries to die on idle transfer.

I've replaced the small pieces of vacuum line that connect the pieces of hardline from the PCV to the EVAP canister, and also from the PCV to the intake. I've replaced the rubber tee on the passenger side of the back of the intake, and also the piece of vacuum line on the drivers side of the intake. All of the vacuum line from the brake booster back to the intake has been inspected and looks OK. I've noticed there are a couple of vacuum trees that are on the firewall just below the wiper cowl; are those problematic? They looked OK at a glance. Maybe the caps are rotten? I would think this would affect brake booster performance but there are no symptoms that appear when I hit the brakes and the booster seems to work fine.

Also the vacuum lines that appear red and green on the diagram on the core support; I've seen one of them, appears to control fuel pressure regulator. Are they prone to deteriorate over time? They appear to be made of nylon.

The symptoms I will certainly grant you guys point to vacuum leak, but I am pulling my hair out trying to finger the culprit.

Thanks again for all the input!
 

·
Premium Member
Joined
·
2,545 Posts
Sorry if this has been suggested already. I'm on my BB And getting ready to head out to the flight line. But have you checked to make sure your MLPS is aligned properly? Or swapped it out with a new one. If its bad and thinks its in park or neutral while in gear it would not command the more air to idle in gear.
 

·
Registered
Joined
·
249 Posts
http://forums.tccoa.com/showthread.php?p=1249852&posted=1#post1249852

That was my battle with p0174, and my advice is check your brake booster hoses and valve as well as all the T's and canisters below the windshield wipers, kinda hard to see.

Speaking of codes, do you have any anymore?

If I am not mistaken I remember being told that the steering power pump goes on when changing from drive and reverse. It's from an old thread where someone said they lose tons of power while trying to parallel park and they wanted to manually change their idle higher, which of course was advised against. I'd recommend flushing the Power Steering fluid, and if it ends up helping, great.

Also while your checking the brake booster plastic valve I would let it suck up some seafoam in there and rev the engine to clean whatever you can out of the system. It's supposed to be between 1/4th and 1/3rd a can, but it's been ill cared for, I'd try going to a half or possible two treatments of the above spaced out.

P.S. If your spraying with carb cleaner (can hurt plastic and rubber, as in your entire vacuum system), I would stop and get a portable propane torch out. The abridged version of my thread is the torch was hard to reach everywhere, I turned it upside down, and only found the broken brake booster plastic valve because the propane got freezing and caused a drip which the booster sucked up immediately. I even seafoamed before this time with that very hose the valve was connected too and still over looked the plastic valve as a possible issue.
 
1 - 20 of 41 Posts
Top