Hesitation and seems to be loading up...whats the deal?

[redneck15431]

Details of my car are in my sig, but I just recently finished up doing everything I wanted to as far as mods (for the time being anyways ). Whenever I blip the throttle there is a hesitation, and at idle the engine has a very little shake to it. I also noticed that whenever I'm revving it, black smoke comes out of the exhaust which makes me conclude that it's running a bit rich or loading up. I am running 93 octane gas in it with the timing advanced about 16*. The car runs like a raped ape but with the hesitation it makes it a little harder to pull out at a stoplight or a stop sign. The car also stalls out sometimes when I push the clutch in coming to a stop, which may be directly related, but I think that may be an issue with the IAC valve due to the cam.

It was like this before the mods too but I really didn't mess with it much before. I don't know where to look at. I got the fuel pressure at about 38 lbs with the vaccum line in. The oxygen sensors are pretty much brand new. I'm thinking that either the MAF and injectors are mismatched, since there was a different intake on there when I bought the car, or I might need a hotter spark plug. What do you guys think?

Thanks.

 

[jrichker]

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is less than $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see http://www.midwayautosupply.com/p-7208-equus-digital-ford-code-reader-3145.aspx– It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

 

[redneck15431]

For the engine off test I got codes 11, 29, 87, none of which make any sense to me.
And for the engine running test I got 12 and 22, 12 dealing with I guess what would be the throttle body or the IAC valve which I expected, and 22 for the barometric sensor. I have no idea what that even is or where it's located

 

[jrichker]

Code 22 is the performance killer.

Code 22 MAP (vacuum) or BARO signal out of range. The MAP or BARO sensor is pretty much the same sensor for both Mass Air & Speed Density cars. The main difference is where it is connected. Mass Air cars vent it to the atmosphere, while Speed Density cars connect it to the intake manifold vacuum. Its purpose is to help set a baseline for the air/fuel mixture by sensing changes in barometric pressure. The MAP or BAP sensor puts out a 5 volt square wave that changes frequency with variations in atmospheric pressure. The base is 154 HZ at 29.92" of mercury - dry sunny day at sea level, about 68-72 degrees. You need an oscilloscope or frequency meter to measure it. There is no way you can use a common cheap voltmeter or DVM to accurately measure the output signal.

The MAP/BARO sensor is mounted on the firewall behind the upper manifold.

Baro or MAP test using frequency meter - run the test key on engine off. The noise from the ignition system will likely upset the frequency meter. I used a 10 x oscilloscope probe connected from the frequency meter to the MAP/BAP to reduce the jitter in the meter's readout.

If it is defective, your air/fuel ratio will be off and the car’s performance & emissions will suffer

Some basic checks you can make to be sure that the sensor is getting power & ground:
Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.
Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery cable. It should be less than 1.5 ohm.

The following power on check requires you to turn the ignition switch to the Run position.
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or EGR sensors. Use the black/white wire for the ground for the DVM.

Code 11 is the computer OK code.

Code 29 - Vehicle Speed Sensor (VSS) is an electronic sender mounted on the speedo pickup gear on the trans. It works the cruse control for both 5 speed and auto trans cars. The VSS is used to tell the computer to speed up the idle as you slow to a stop. This helps keep the engine from stalling when you slow down for a stop sign or stop light.
Check to see if the electrical connector is plugged into it. Clean the connector & contacts with non flammable brake parts cleaner prior to replacing the sensor, as that may fix the problem. The sensor cost is under $30 and it is easy to replace.

Code 87 – fuel pump primary circuit failure. The fuel pump lost power while the engine was running. Check fuel pump relay, check inertia switch, wiring to/from inertia switch, red wire going to inertia switch for +12 volts. Check the other side of inertia switch for +12 volts.

To help troubleshoot the 87 code, follow this link for a wiring diagram for 89-93 cars http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp

For 79-88 cars use, http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp

 

[Skoobie]

Wow...if you DO figure out what your issue be sure and post it. I have nearly identicle mods (except the headers) to you and Im having the same issue, only I think mine is more pronounced. Keep us informed. If I figure out mine I'll let you know

 

[redneck15431]

Ouch...it's about $87 for a new barometric sensor...I'll borrow one before I buy one.
My TPS voltage was .81 so I adjusted it to where it's bouncing back between .97 and .98. That gave it a lot more snap but it still has a hesitation problem yet. I'm going to tinker with the timing a little bit...and maybe some hotter spark plugs? I highly doubt it's anything to do with the fuel pump/filter since it's running rich. If the fuel pump was cutting out or the fuel filter was clogged it would make me run more lean...or just not run at all
Actually, when idling when the car is fully warm, the exhaust does not smell at all. Only when revving it is when I see the black smoke.
I'll spend some time on it tomorrow.
I'll definately keep you informed.
Thanks everyone!

 

[Aliate X]

try cleaning your MAF with some rubbing alcohol and a q-tip.

 

[Black1987Stang]

another vote on cleaning the maf

 

[redneck15431]

I cleaned my MAF and my IAC valve yesterday, and did not do anything. So I started to mess with the timing and tried to get it in time without a timing light by listening to the engine, even though I did have one handy. That did not work so I stopped and began to work on other things while I thought about it.

So today I used a timing light and it turns out it was WAY off. Like 10* or 14* retarted. So I set the timing at 12* with the spout out and the engine got real calm. It has a lot more snap to it now and the hesitation is almost non-existant, but it still has...I dont know how to put it...like a surging rev. When I blip the throttle and let off, the RPM's go up, stop (like a hesitation) and go up again. Although when I blip the throttle and hold it in, it rev's quickly without hesitation.

I'm going to work on it some more and I'll keep you guys posted.

Thanks everyone.