I apologize ahead of time for rambling, not a lot of coffee intake this morning

Last Saturday I flew down to southwestern Florida to pick up a semi running Monster Miata conversion. The seller was a nice enough young man, more in to Lotus Elise's than Miatas. Did the deal, swapped my plates on, and away I go in the light drizzle on almost worn smooth 245/45/15's tires. Figured I'd hit the nearest major tire retailer and replace them along the way. Well, at least I thought I would be able to as it appears that these are not stocked anywhere except a TireRack warehouse. Ok, so I'll drive carefully, and use the gas pedal with a featherlight touch. No problems for the first few miles before the car starts bucking and surging sporadically, stop on the side of the road and pop the spark-plug wires (one on each side) back on to their plugs as snug as I can. Get on RT75 and start the 11+ hour trip towards home. Of course on the highway, at 2,300rpms, the motor runs pretty smoothly so I don't give it much thought, that is of course till I get off for fuel (100 mile intervals at this point) and the car stalls at the bottom of the exit, barely able to restart. After three stops I'm really starting to have concerns, after I see light wisps of smoke filling up the car and wafting out behind the car (more on that later), I decide that I am close enough (about 40 miles) from my good friend Steve's house (cruizin54) and decide I'm going to take a chance and get off RT75 and head westwards towards his place. Again, bucking and kicking the whole way there, one foot for the gas to keep the revs up, the left foot for the brake and clutch. Steve and his wife Joan graciously open their home to me so I have a warm bed to sleep in. Steve calls his friend Dan over who gives us some basic ideas via flashlight at 9pm. The next morning we head out for tune up parts (always start with the basics), new plugs, wires, cap rotor,pcv valve, fuel filter. tailshaft seal (Dan suggestion). Do all but the filter and seal in his driveway the next morning, no wispy smoke at all, no drips under the car, car still running horribly once warm. Take it over to Steve's friends Brian's house, who has a new Bendpack scissor lift so we can really inspect the underside of the car. Turns out Dan is right, the tailshaft seal is leaking, of course right where it is leaking, is also where the crossover pipe is, hence my wisps of smoke. So with a lot of effort, Steve and I change the tailshaft seal (Steve doing most of the hard work ), and drain and replace the transmission fluid (2 quarts drained, 2.8 quarts reinstalled), which at this point, due to a loose hose on the fluid pump, Steve and I are now wearing, again Steve getting the brunt of it . By now it's late on a Sunday afternoon, and we were in no mood to mess with it any longer. 7am Monday I pack up and head out to the local repair shop so they can install the fuel filter, maybe plug in and see what is going on with the motor. Well, filter goes in just fine, but no signal from the TPS...Damn, damn, damn.Well, I have to get home tonight (another 500+ miles), I've run off just the Mass Air signal for this long, might as well give it a shot.......Back on the highway, and now getting pretty good with the modified three pedal shuffle, even in the rush hour traffic I hit around Atlanta, I never stalled the car once. Rolled in to the house around 8pm Monday evening. park the car and just leave it to sit while I gather my thoughts and clear my head.

Tuesday late morning I head out to once again review what has been done, and what I might have missed. Sure enough, a few cracked vacuum lines, and funny, no vacuum line to the MAP sensor!!!!!!!! How could I have missed this, well, it turns out that not only was there no vacuum line to the sensor, but no cap where the old vacuum line "T" used to be connected, and no spout on the MAP sensor to even install a vacuum line to.....Also find a broken wire to the TPS, repair that and I am awaiting my new MAP sensor to arrive early this afternoon. Changed out a bunch of vacuum lines to play it safe, got rid of the "T" connector altogether and will take vacuum off the correct upper intake port for the MAP input. Really hoping that this straightens things out, as I've gone over everything else and cannot see anything else that could be wrong...Will leave the codes in the computer for now (I'm sure there are over a dozen), install the MAP sensor and borrow a reader to see what else I can find.

Again, what a long strange trip it has been so far.

Bill S.

 

Kinda makes one wanna put a carb on it. Once EFI/computer stuff starts failing, seems like a never ending nightmare...even with tuning software.

We went carb last year for that very reason. Got tired of throwing money @ engine codes.

 

This is my 7th monster miata, 4 builds, 3 rescue/interventions. Someone spent a lot of money on the original build, second owner spent a little more and probably got scared off by the lack of proper running engine. I like a challange and I am not afraid to take a chance every now and then.

Off to get my parts, will post later with the results.

Bill S

 

...and pictures!!

 

I tuned for 7 yrs using EFI live tuning software. It's not that I can't, it's that I choose not to.

 

MIL for the EGR delete will be here Monday, MAP is in, new vacuum lines are on, but no mileage on anything to let the computer "relearn" Cars runs much better, still a warm idle surge, will deal with that on Monday when I have the time.


Bill S.

 

Just two for now as it is not high priority at the moment

Paint is a good three footer


Bill S.

 

Looks good. What are your plans for this one? Keep or re-sell?

 

If your car has a mass airflow sensor, it does not have a MAP sensor. It is a BARO sensor, & it does NOT get a vacuum line attached. The MAP sensor is used on speed density cars only (1986-1988, non-California).

 

See step #8. http://static.summitracing.com/globa...n-81868801.pdf Sorry, I could not find the instructions for the kit from Ford.

 

Bill S.

 

Just went out to the garage to double check my work, you were 100% correct, BAP sensor without a vacuum line attached. Not sure where my head was when I wrote the previous post, even the receipt for the sensor shows it as a Barometric Pressure Gauge


Bill S.

 

The MAP & the BAP are the same exact part# when purchased from Ford. When used as a MAP sensor, it requires manifold vacuum. When used as a BAP sensor, No vacuum is applied. The port is left open to sense barometric pressure as noted in step #8 http://static.summitracing.com/globa...68801.pdf.when adding mass air to a speed density car. By removing this vacuum hose, the MAP becomes a BAP. I had to "fix" quite a few of these as a Ford tech back in the fox-body heyday of the mid 90's. I am sure I have an EVTM (electronic, vacuum, troubleshooting manual) for a 1992 Mustang around here to confirm.

 

Cool!!. From the sound of your running condition on your first post, I would have guessed it was a bad TPS. I have seen thousands of those over the years. I had a new Motorcraft one (less than 3000 miles, but installed in 2007) go bad last year on the only day I drove it.

 

Just a little blood and sweat today

Have not even adjusted the TPS yet, went to get my multimeter out, only to find that whoever borrowed it from me last failed to tell me they ran it over . Although they were nice enough to put it back in to it's carry case for me.

Instead I cleaned the Mass Air wire (electric contact cleaner) today, same goes with the IAC (throttle body cleaner), swapped out the BAP, replaced the vacuum hoses, and fired the car up and took a quick ride around the block (still on rock hard, almost bald tires). Not quite idling the way I want it, but much better than it was.

 

That depends on if my Laguna Blue 1994 "R" sells or not. If it does, then I'll, hold on to this one for a while. if not, then I'll work the bugs out, give it a good cleaning, repair whatever else I find, then put it on the market come late spring.


Bill S.

 

Bill, really glad we were able to help you out. For those who think that without a picture it didn't happen, here is that proof (this was before I took a shower in Mercon V). I'm also glad to have friends like Dan and Bryan!