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Car Forum / Ford / Ford Mustang / August 20045.0 Thunderbird hesitation
Hello all. I'm having some minor problems with my 5.0l in my 88'bird. In park, when I rev the engine, I get some hesitation/skipping/popping at certain rpm. It starts off around 1200, disappears about 1800-2000, then comes back harder from 2300-2600 rpm. But ONLY during those times. Will go all the way to 5500 from there with no problems. Also, when driving down the road, if I am just barely touching the throttle, it will skip and hesitate some. When driving like normal, or hard acceleration, there's nothing - smooth as glass almost. I have checked the timing (seems happiest at 12` btdc). New wires, plugs, air filter, replaced the timing chain when the cover gasket failed (6 months ago). There are no mods to the engine (hopefully rebuilding soon!!!) except for a 65mm tb +67mm egr, MSD 6A, and MSD tfi coil (both 1.5-2 years old and eat 75 amp alternators for breakfast!). Thanks for your time in reading this, and hopefully someone may have some answers! Sounds like it could be your Throttle Position Sensor going bad. It can be tested on the car with either a Volt or Ohm meter. I don't remember which wire is which but someone here will be able to offer a detailed testing procedure.  SignatureMike Silver 10th Anniversary Cobra Coupe --- > Hello all. > [quoted text clipped - 17 lines] > Thanks for your time in reading this, and hopefully someone may have > some answers! If you want to test the TPS you will need to get a volt / ohm meter and set it to read volts. Take a needle and perice the green wire , do not let the needle touch anything metal on the engine once the wire is periced. Take your Red wire from the meter (+) and clip it on to the needle. Take the Black wire from the Meter (-) and Ground it to anything metal like the throttle body. Once done take you key, put it in the ignition turn the key forward into the Acc "ON" position . Do Not Start the car. Look athe digital meter and see what it is at. You normally set the TPS like this, however this will not tell you if it is good or bad. Your TPS if it has high mileage on it could very well have some dead spots inside it . Replace it and when you put the new one on set it with the above info. You may have to take a drill and wobble out one or both of the holes on the TPS so you can twist it to get the desired setting. Each car is different. Settings are best around 9.7V to 1.5V on the meter. Once you get the desired setting screw it down on to the throttle body and look at you meter to see if it stayed at the setting you wanted. If not loosen it barely then twist the TPS and screw it back on. About you alternator, the factory 75amp alt is a piece of trash, I burned though a sh.t load back in the day. Go buy a 1993 Ford Aerostar V6 3.0L 95 amp alternator with 6-groove pulley. It has the same bolt pattern and will be the cure for that old 75 amp design. It has an internal fan and is internal regulated. The only thing you have to do is cut the three wire square power plug off and crimp Ring connectors on the two black (+) wires and get a stator pigtail connector for the stator wire. See the newer 95amp alternator is a one wire type, take the two blk (+) wires with the Ring connectors and slip them on to the bolt and tighten it. Slip the third wire the skinny wire (stator wire) on to its connection then Install the alternator and belt and you are done. >Sounds like it could be your Throttle Position Sensor going bad. It can be >tested on the car with either a Volt or Ohm meter. I don't remember which >wire is which but someone here will be able to offer a detailed testing >procedure. > If you want to test the TPS you will need to get a volt / ohm meter > and set it to read volts. Take a needle and perice the green wire , [quoted text clipped - 7 lines] > it is good or bad. Your TPS if it has high mileage on it could very > well have some dead spots inside it . You test it the same way by slowly opening the throttle. The V should go up smoothly in proportion to the throttle opening. Bad or dead spots will show the V bouncing around or droping to 0v. The Ohm meter testing is done similarly with the key off and the TPS unpluged. Attach the leads to the green and orange wires at the TPS plug. The resistance should go down smoothly as the throttle is opened, bad or dead spots will show the ohms bouncing or going to open. >Replace it and when you put the > new one on set it with the above info. You may have to take a drill > and wobble out one or both of the holes on the TPS so you can twist it > to get the desired setting. Each car is different. Settings are best > around 9.7V to 1.5V on the meter. The setting should be below 1v, 0.97 to 0.98. IIRC, the computer thinks the throttle is open at 1.2v and above. >Once you get the desired setting > screw it down on to the throttle body and look at you meter to see if > it stayed at the setting you wanted. If not loosen it barely then > twist the TPS and screw it back on. SignatureMike Silver 10th Anniversary Cobra Coupe --- >The setting should be below 1v, 0.97 to 0.98. IIRC, the computer thinks the >throttle is open at 1.2v and above. Are you sure about that ? For a long time I always thought that the best setting was .999v . I aquired Mustang Performance Handbook and Mustang Performance Handbook 2 (by William R. Mathis) from a buddy about five yrs ago. In Vol 1 they recomend playing with settings from 1.5 down to 9.7 or so. >> If you want to test the TPS you will need to get a volt / ohm meter >> and set it to read volts. Take a needle and perice the green wire , [quoted text clipped - 30 lines] >> it stayed at the setting you wanted. If not loosen it barely then >> twist the TPS and screw it back on. >> The setting should be below 1v, 0.97 to 0.98. IIRC, the computer >> thinks the throttle is open at 1.2v and above. [quoted text clipped - 4 lines] > about five yrs ago. In Vol 1 they recomend playing with settings from > 1.5 down to 9.7 or so. It's been a while, I know .99 is suppose to be the best setting but I could have swore the 1.2v was the highest before the comp thought the throttle was opened. I also read somewhere that the EEC-V took the reading at start-up (below the throttle opening threshold) and used it as a baseline, setting it makes no difference on the newer engines. SignatureMike Silver 10th Anniversary Cobra Coupe --- Christopher Wall opined in > There are no mods to the engine (hopefully rebuilding soon!!!) except > for a 65mm tb +67mm egr, MSD 6A, and MSD tfi coil (both 1.5-2 years old > and eat 75 amp alternators for breakfast!). your symptoms are classic spark system mismatch, Restore all the "Hot Rod" pieces to stock, including wires, and install motorcraft regular plugs and i will bet it goes away to save money, just go to a scrapper and pull good looking stock pieces. arghhhh. did you just notice this AFTER you changed the timing chain? This is a classic one-tooth off symptom > arghhhh. > > did you just notice this AFTER you changed the timing chain? > > This is a classic one-tooth off symptom Actually, I noticed a little bit of roughness after having my car returned from a trans re-rebuild (The first guy apparently didn't know wtf he was doing...fried the whole aod in less than 6months!....and he still expected me to pay full price again!). I didn't think much then, it wasn't really bad. Didn't really change any after the timing chain was replaced, and has just gotten worse over the past 8-12 months. Just a nagging annoyance, but the skipping while driving is recent-- last week or so. Please tell me it's not the chain! lol I'll check the tps as soon as I figure out where I put the meter. But of course, all things being so pleasant this month, my analog cluster quit working this evening (only the speedo and tach work, everything else has no reading) The fuses all look good....ground fault somewhere? Christopher Wall opined in news:90dXc.249525$OB3.24789@bgtnsc05- news.ops.worldnet.att.net: > Please tell me it's not the chain! lol I'll check the tps as soon as I > figure out where I put the meter. But of course, all things being so > pleasant this month, my analog cluster quit working this evening (only the > speedo and tach work, everything else has no reading) The fuses all look > good....ground fault somewhere? prolly not the chain... disconnect spout, use timing light and look for flutter in timing marks or lite misfire. but i've had lesser noted symptoms of the same when bosch plats were installed in my fords. started afte about 1000 miles on plugs. so i'd start back at ground zero as far as the ignition goes... spark enhancers on that car is eye candy or brag stuff, anyway. And I've had new plug wires returned in two different cases. either a ground in the cluster/steering column area or a bad cluster voltage regulator... little three terminal part on the back of cluster, may have what looks like 9volt battery clips... dont rule out fuse, though, use meter or test lite on the little metal bits top of fuse. > prolly not the chain... disconnect spout, use timing light and look for > flutter in timing marks or lite misfire. [quoted text clipped - 10 lines] > looks like 9volt battery clips... dont rule out fuse, though, use meter or > test lite on the little metal bits top of fuse. Yeah, I had those bosch platinums in there untill about a 5 days ago. Went back to copper plugs, std. 8mm wires. Is there any real way of testing the wires to see if they're possible culprits? An ohms reading, or continuity test? I found my volt meter tonight, so after work tomorow I"ll start checking things. As far as the cluster in concerned, I'm thinking a bad ground/power or, as you mentioned the regulator. The gauges all started working(somewhat erratically) today. Kept working, then fading out, nothing, then spikied, stayed at a regular reading, but only for a short time. Went back to being erratic (either pegged up, or almost nothing for the most part). Regulator??? If I remember, when pegged, they are grounded out? |
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