96 D21 2.4L Horrible Throttle response

[Oneshot1984]

Ok, New guy on the NICO here.... so here's what I've got
1996 Nissan hardbody, 2.4L 5 Speed manual, Mfd in 4/96 so its just like the 97, 2 Wd, 144K miles, original owner, I'm an Old Moss back and I don't drive it over 65 mph, was running perfect, smooth, no issues, I could eat off anywhere under the hood, super clean, west coast car, no rust,salt or corrosion, no accidents, it was my baby until 2 weeks ago,,, I was cruising down the freeway 60 mph, been on the road 45 minutes, nice flat stretch of highway...instantly lost power, stumbled a little as it was powering down, my first thought was there goes the fuel pump after 144K miles
Would not re-start on freeway, towed home........ next day, No trouble codes,,But I do have a factory shop/service manual that I bought when I bought the truck new,, I checked fuel pump, found it was OK, started it up, idled rough and would not take rapid throttle, I then checked fuel pressure at injector rack OK around 40 lbs and witnessed the fuel pressure regulator operate OK as the engine will run up to high rpm if throttle is gradually rolled on and I can watch the regulator hold pretty constant pressure..... With my gauge dead headed down stream of the fuel filter the pressure holds at 65 lb with not much leak down. I checked the throttle positioner and it outputs a nice linear signal as per the book, even when I stab the throttle, I did this many times looking for a flakey signal, I checked and re-cleaned all the grounds I could find,,,,,exercised and reseated every connector on every sensor,,,, I checked the output of the MAS, it showed good but I replaced the MAS, I had one already, unsure if my original Hitachi is bad, seem to run a little smoother..... everything was spotless in and around the throttle body, I took off the top of the throttle body to insure the gasket was intact, it was....I looked for obvious vacuum leaks, found none, I replaced the coolant temp sensor as it seem it had a little more resistance than the specs called for,,,,, I inspected the cam positioner inside the distributor, it was spotless, I blew it out with compressed air anyway...I did not pull the crank positioner sensor as I read it is used to just assist the ECU on trouble codes not on actually controlling the engine run..The problem acts just like a carburetor without the accelerator pump, it idles smooth, if I roll the throttle on up slow it ramps right on up, if I'm about 2k rpm and I stab the throttle it just friggn gasps like its outta fuel and will die if I don't drop the throttle back and let it catch itself..It will rev up to the red line if I don't stab it and do it slowly........ all the while no codes and yes my CEL works cause I pulled of the O 2 sensor at the exhaust manifold and it knew that and was not happy, I reset that. This is mainly all easy freeway miles, I just now fed it some new NGK's because it was due, but it runs too good to be an ignition problem in my thoughts, sounds just like the ECU is not recognize the TPS signal and not delivering the fuel..... I am now in the process of measuring the pulse width or the amplitude in which the ECU provides a great amount of fuel when it thinks it should, either it provides a higher voltage for more current to open the injector more or it provides the injector with voltage for a longer duration or a combination of both..... of which I do not know yet......... so I can't be the only guy out there where there are no codes, engine sensors all appear to be good, runs smooth at idle and if throttle is increased slowly still runs smooth, but can't take a quick mash to the floor........ I have not driven it to see if the power is there on a slow ramp up of rpm,,,,, I just don't feel like maybe having to get towed home.... my last thought is I'm kinda leaning that the ECU is not seeing the TPS or it is and not reacting....... this Nissan is kicking my arce !
Does anybody have any ideas or similar experiences
Thanks guys..... I love reading some of the posts, I know there are some really great wrenches out there
Cheers
Carey

[Oneshot1984]

Tomorrow, I'm going to feed it a bit of starting fluid as it dies to confirm a fuel issue, I will monitor the spark as well with an external spark pick up monitor just to insure with the added stress of full throttle the spark is good

[Oneshot1984]

OK I found the culprit...... here's what I did, I was positive it was a lack of fuel issue, but I was married once and remembered I was fooled then too..... so I decided to keep my eyes open and leave every possibility as a possible link to the problem or it be the problem...... I put on a timing light on number one cylinder, since all the cylinders were dying, it didn't really matter which one had the light..... fired it up, ran perfect, ramped up the rpm, nice linear curve, not a miss, light blinking almost pure steady on......up to about 3500, ramped down to about 2 k, punched the throttle, engine coughed, light went out ! ahhhhh I said, not a fuel issue like I thought... a friggin ignition issue..... backed off the throttle before it died completely, it caught itself and idled right down, repeated test, same results............checked for solid 12 volts to the ignition side of condenser with key on and rpm stabbed up and down, it was fine, checked for solid 12 volts at cam position sensor with rpm stabbed up and down, it held solid as well...... so it looked like it was time to dig into the distributor which I did.... found a hole burnt in the coil which was leaking to distributor case, its an obvious leak and I feel very certain that is it, looked like someone had done some arc welding, that's how bad it was.........I've got some parts on the way, then well see 100 percent.....it had me fooled, when it would cut out there was no popping or back firing like I would have expected, I also believe since there was so much arcing going on that it also was confusing the optic read diodes for the cam positioner sensor which live next to the coil
I hope this may help a fellow Nissaner in the future
I have a pic of the hole in the coil, but have to figure out how to post it.......

Cheers

[Oneshot1984]

Here's the update, I received a new coil today in the mail, Nissan won't sell just the coil, you must buy the whole distributor, so I turned to Ebay and found what appears to be OEM, it has CMITO-227 just like the OEM coil, maybe a clone from China..... anyway installed it, runs perfect, took it out for a 30 min spin, still running superb, so I'm gone, until next time
Godspeed

[1996D-21]

In a roundabout way ,thank you for the help ! I have virtually the same problem with my '96. And I haven't gone that far yet - to check the coil ! Brilliant ! Let everybody know what happens .

[Desert Rat]

good job tracking it down. I was reading the first post and I was going to suggest ignition....glad you got it sorted out.

[mouse53]

Good work hunting that down and very thorough too. I especially like the part about working on these is like being married once and being fooled, LOL. Been there and done that. My 91 D21 did the exact thing running down and open road about 55 then just dies off , except mine will not start at all. I'm thinking fuel pump since I don't hear mine run at all , but hate removing the tank if I don't have to. Shop here says $500 for the pump and another $300 to install, no way I'm spending that much, I'll do it my self. I have checked the relay and most everything fuel related, and it has spark. I can't see why you couldn't run and external pump, but shops says no because the existing pump will not let the fuel pass from the tank. So I 'm stuck until I find out more, don't want to start changing parts if I don't know for sure what the problem is.