I have a 98 mustang gt 5 speed, cai, upr x pipe, and flows. I just put a engine out of another car because my old one was knocking. Same year engine and all,basically a short block. So I switched everything from the old engine to the new one, now when I start it, it will idle ok than start surging pretty bad and shaking around. New plugs are in it, tried driving it and it has no power... I data logged it earlier and the maf voltage is reading 0, also the fuel rail pressure and fuel source are all reading 0. I don't know where to go from here without just replacing things.
98 mustang surging idle and no power
- Thread starter paulwahl88
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This is a tough one. If I had to guess under normal circumstances, it sounds like a TPS problem. (Throttle Position Sensor.) Since you just swapped a lot, it is most likely a vacuum leak. Check those little hoses. Something is probably not connected or cracked.
trinity_gt
10 Year Member
Since you just swapped the engine you might want to verify that none of the wiring harness got pinched or damaged during the extraction and re-installation. A P1261 suggests a short in the harness, at the injector or in the PCM. Given the work that was just done I would start looking carefully at the harness...
wmburns
SN Certified Technician
First, is the engine grounding strap from the motor mounts to the body frame rail connected?
Have all of the fuses been checked and confirmed good? Especially the EEC fuse. With the MAF and other powered sensors reading ZERO, a fuse or disconnected wire should be very high on the list (esp after a motor swap).
Perform a through visual inspection of the wiring harness and the connectors that were worked on. There are a few small single and double connectors under the battery that are easy to over look.
Confirm there is +12 volts on the MAF red wire with the key on. If not, STOP and find out why (see above).
The fuel injectors circuit is a "ground start" circuit. This means that the device is activated by grounding the return signal line. One of the diagnostic tests for a ground start circuit is there should be +12 volts at the device at all times.
At each fuel injector there are two color wires (my wiring diagram program is not working for the 98 MY). One color will be the same for all injectors. The other will be different. With the key on, confirm there is +12 volts to each fuel injector with the same color wire.
Now turn the key on but do not start. Repeat the same test on each fuel injector but this time on the different color wire. Should be around +12 volts. Post if not.
Next test requires a "noid" style test light. Start the motor. Place the noid tester across each fuel injector. The tester should flash with each injector pulse. What we are looking for is injectors NOT pulsing or are pulsing all of the time. Post the results. Ofen the combination will give clues.
OBTW, ignore the P1000.
Have all of the fuses been checked and confirmed good? Especially the EEC fuse. With the MAF and other powered sensors reading ZERO, a fuse or disconnected wire should be very high on the list (esp after a motor swap).
Perform a through visual inspection of the wiring harness and the connectors that were worked on. There are a few small single and double connectors under the battery that are easy to over look.
Confirm there is +12 volts on the MAF red wire with the key on. If not, STOP and find out why (see above).
The fuel injectors circuit is a "ground start" circuit. This means that the device is activated by grounding the return signal line. One of the diagnostic tests for a ground start circuit is there should be +12 volts at the device at all times.
At each fuel injector there are two color wires (my wiring diagram program is not working for the 98 MY). One color will be the same for all injectors. The other will be different. With the key on, confirm there is +12 volts to each fuel injector with the same color wire.
Now turn the key on but do not start. Repeat the same test on each fuel injector but this time on the different color wire. Should be around +12 volts. Post if not.
Next test requires a "noid" style test light. Start the motor. Place the noid tester across each fuel injector. The tester should flash with each injector pulse. What we are looking for is injectors NOT pulsing or are pulsing all of the time. Post the results. Ofen the combination will give clues.
OBTW, ignore the P1000.
I checked all of the fuses, under the hood and inside, all are good. The fender to engine mount ground strap was broken so I replaced it with 4g wire, and the harness to engine mount ground is ok. The maf seems to be getting power to it now, cleaned all the connectors with electrical cleaner, and retried, it runs a little better but still not even close to right.. Now on the injectors all of the red wires have 12 volts to them with the key on, the other wire on each injector which are all different colors as you described have no power to them with the key on. I'm going to check all the wires again, I already have a hundred times but I have nowhere else to go from
wmburns
SN Certified Technician
What did you do to correct the power at the MAF? Confirm there is +12 volts at the TPS with the key on.
If you datalog it, are you still seeing the MAF at zero?
If you datalog/monitor the O2 sensors, what do you see?
Are there any pending DTC's? If so, what are they?
Did the scanner ever show anything for the fuel pressure. This is a return system right?
Recommend double checking the two large engine harness connectors. Also check the PCM connector. Look for bent/pushed pins. Corrosion, water damage.
Personal experience story follows-
When my Son and I replaced the motor in a F150, we pinched an O2 harness pigtail between the motor and transmission. The motor would start but run like crap at anything above an idle.
The ODB2 scanner told us that many powered sensors were not reporting values. A blown fuse was one of the the first things thought of. We checked and couldn't find any blown fuses (or so we thought).
A full day of trouble shooting the wiring harness followed with no real results. Finally we rechecked the fuses and found the overlooked blown fuse. From there, the circuit was traced until the pinched harness was found.
The point is I'm speaking from personal experience. It's easier than you think to over look a blown fuse. We would have saved a ton of time and alot of hair pulling had we found the blown fuse the first time.
If you datalog it, are you still seeing the MAF at zero?
If you datalog/monitor the O2 sensors, what do you see?
Are there any pending DTC's? If so, what are they?
Did the scanner ever show anything for the fuel pressure. This is a return system right?
Recommend double checking the two large engine harness connectors. Also check the PCM connector. Look for bent/pushed pins. Corrosion, water damage.
Personal experience story follows-
When my Son and I replaced the motor in a F150, we pinched an O2 harness pigtail between the motor and transmission. The motor would start but run like crap at anything above an idle.
The ODB2 scanner told us that many powered sensors were not reporting values. A blown fuse was one of the the first things thought of. We checked and couldn't find any blown fuses (or so we thought).
A full day of trouble shooting the wiring harness followed with no real results. Finally we rechecked the fuses and found the overlooked blown fuse. From there, the circuit was traced until the pinched harness was found.
The point is I'm speaking from personal experience. It's easier than you think to over look a blown fuse. We would have saved a ton of time and alot of hair pulling had we found the blown fuse the first time.
I'm guessing the broken frame rail to motor mount ground was the problem because the maf reads 12 volts with the key on now.Maf still reading 0 when logging with live link. Fuel rail pressure still at 0. Fuel source went to 4 than averaged at .316922. Bank 1 O2 averaged .07856, Bank 1 rear .00091, Bank 2 front .074889, Bank 2 rear .005403. I didn't unplug any of the main harnesses I'll check them anyway though.
wmburns
SN Certified Technician
Regarding the fuel pressure reading. 96-98 is a return system with a mechanical regulator. There is no fuel pressure sensor. I suspect the PID has no value because there isn't a sensor for this application.
What I wanted to know about the O2 sensors is if the values change.
I would not thought it was possible to remove the motor without disconnecting the two large engine harness connnectors near the right hand fire wall.
The MAF air flow being zero is a real problem. Of course it will never run right until the PCM sees this signal.
You didn't answer the question about other DTC codes.
Measure the key off resistance from the MAF black wire back to the battery negative. Should be low. Post.
What I wanted to know about the O2 sensors is if the values change.
I would not thought it was possible to remove the motor without disconnecting the two large engine harness connnectors near the right hand fire wall.
The MAF air flow being zero is a real problem. Of course it will never run right until the PCM sees this signal.
You didn't answer the question about other DTC codes.
Measure the key off resistance from the MAF black wire back to the battery negative. Should be low. Post.
I checked both connectors, no corrosion or anything like that. The only dtc is the p1000, and a p1260 for the immobilizer, but the 98 my just immobilizes the starter correct? So i don't see how that would effect anything. Im going to need to see if I can buy or borrow a dvm because the ohms isn't working on mine. As for the O2's the reading were moving, idk what they should be at though.
I checked the resistance between the maf black wire and negative battery, it's reading 0.00 ohms. I also have a lean code PO174, thinking it has something to do with the maf not reading. Pulled the plugs too for the hell of it, 1 in each side bank was clean, like new looking, making me think they aren't firing, guess the wires may not be good also.
wmburns
SN Certified Technician
Confirm if you have spark first. If so, then likely you have installed the spark plug wires incorrectly at the coil pack. That's the kind of mistake that can happen during an engine swap.
If you are sure the spark plug wires are correctly installed, post the cylinder numbers with the problems. Sometimes that can provide clues as to what is wrong. For example, if the two cylinders are "paired" together at the coil, then this points to a common problem in the coil secondary/primary.
Double check that the coil pack low voltage connectors are good. No bent/pushed pins.
I agree that a lean DTC would result if the MAF is reporting/under reporting the air flow. It will never run right until this is fixed. Has any "mods" been done to the MAF or MAF electrical connector?
For a test, disconnect the MAF electrical connector. Does this improve how the motor runs?
I'm assuming the original P1261 DTC is gone.
Just wondering, did you forget to disconnect the engine ground strap before pulling the motor?
If you are sure the spark plug wires are correctly installed, post the cylinder numbers with the problems. Sometimes that can provide clues as to what is wrong. For example, if the two cylinders are "paired" together at the coil, then this points to a common problem in the coil secondary/primary.
Double check that the coil pack low voltage connectors are good. No bent/pushed pins.
I agree that a lean DTC would result if the MAF is reporting/under reporting the air flow. It will never run right until this is fixed. Has any "mods" been done to the MAF or MAF electrical connector?
For a test, disconnect the MAF electrical connector. Does this improve how the motor runs?
I'm assuming the original P1261 DTC is gone.
Just wondering, did you forget to disconnect the engine ground strap before pulling the motor?
All of the wires are routed right both on the coil packs and at the spark plugs. I tested the coil packs primary and secondary, the p/s coil pack primary is .06, and .07 ohms which is in spec, the secondary at the coil towers are both over 14,000 ohms which is way out I believe. The d/s coil pack is .05, and .06 ohms also in spec, the paired towers on that side are also over 14,000 ohms. The coils are putting out spark, I removed the wire and put a spare plug in it while the engine was running and once grounded its deff sparking, same when I moved the coil end of the wire near the coil tower, I have spark. When I remove a wire the engine runs the same though. Maf unplugged changes how it runs as it should, so idk whats going on with this car, its my only vehicle so I kind of need it lol and right now its undriveable.
Btw yes the P1261 is gone, and I disconnected the ground before pulling the engine
Btw yes the P1261 is gone, and I disconnected the ground before pulling the engine
wmburns
SN Certified Technician
If the PCM is not seeing a signal from the MAF, then the lean will result. It runs better when the MAF is disconnected because the PCM uses default values. So this confirms there is an issue with the MAF.
You did not power post which cylinders are misfiring. IMO, likely the spark plugs are not connected correctly at the coil packs.
You did not power post which cylinders are misfiring. IMO, likely the spark plugs are not connected correctly at the coil packs.
Well I decided to do a compression test on those two cylinders that seemed to not be firing, sure enough they have 0 compression just free spins. It's cylinders 1 and 6, all the rest have around 180 psi, I figured the timing was off so pulled the cover again, removed the chains and started over. My question is when I setup the d/s I move the cam so it lines up with the mark on the chain and crank gear, then when I release the cam gear the cam turns to the right which in turn puts slack in the straight side of the chain??? Am I doing something wrong? The p/s once I lineup the marks the chain is tight on the straight side. I'm just all confused with this car, it might be going for sale real soon.
wmburns
SN Certified Technician
Pictures would be nice. The timing procedures on the 4.6 are complicated and the steps are important.
Did you mark the chains?
IMO, there are more serious issues causing zero compression. I don't think it's possible for the motor to be incorrectly timed such that two cylinders would read ZERO and the others are OK.
Look for bent valve, broken roller/follower.
Did you mark the chains?
IMO, there are more serious issues causing zero compression. I don't think it's possible for the motor to be incorrectly timed such that two cylinders would read ZERO and the others are OK.
Look for bent valve, broken roller/follower.
Yup it had bent valves in those two cylinders. The seller forgot to mention that I guess huh lol. So I still had the old engine and nothing was wrong with those valves, so I cleaned them up and lapped em, threw em in the other heads. Its going back together so we'll see how it goes this time.
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