Hot-start issue with EFI - who has it, who doesn't

[Zed Head]

0 280 150 116 is the Bosch part number. I ran a set of those for a while. They seem to be the design that Nissan modeled their injectors on. They have a more vaporous injection pattern than the Nissan injectors, not that it seems to matter to performance.

In your third picture isn't that an A46 - 00? I've not seen any over here that have JECS molded in to them, although I have seen a few ECU's and AFM's with JECS labels. I think that Nippon Denso was making most of these kinds of products for everybody in Japan back in the 70's. I've wondered if the JECS label goes on replacement parts or factory production parts.

[EuroDat]

0 280 150 116 is the Bosch part number. I ran a set of those for a while. They seem to be the design that Nissan modeled their injectors on. They have a more vaporous injection pattern than the Nissan injectors, not that it seems to matter to performance.

In your third picture isn't that an A46 - 00? I've not seen any over here that have JECS molded in to them, although I have seen a few ECU's and AFM's with JECS labels. I think that Nippon Denso was making most of these kinds of products for everybody in Japan back in the 70's. I've wondered if the JECS label goes on replacement parts or factory production parts.

I knew the injectors in the car were not original 280Z, but I didn't know they were Bosch.

The A46-00 is correct. I managed to take a photo of the only one with unreadable text. I don't know the history of the JECS injectors, only that I replaced them with the remanufactured "bosch" injectors.

Maybe the bosch came originally out of a Alfa romeo GTV6, BMW E12 or something similar? They used the Bosch injectors and Im told they are a bolt-in replacement.

Chas

[Zed Head]

The 116 injectors seem to be the common replacement from back when people knew how to work on these engines. There must be a list or document out there that the mechanics had. FastWoman said that she had a set on 1975 car in the past, and I've seen them on several salvage yard cars. I actually picked up a full set from a salvage yard from a ZX. They worked great for about a year until one sprung a leak at the pintle. I'm 99% sure that 105 - 116 are the same injector except for hose length, based on the flow data that's out on the interweb. I keep my eyes open so that I can get one more to replace the leaker. They're used on VW Super Beetles with fuel injection, a few old Volvos, some BMW's and some Fiats. In case my experiment with 90's era injectors doesn't work.

Edited April 11, 2014 by Zed Head

[hr369]

this is what jeep did to prevent heat soak. notice the insulation is only in

the center of the manifold. the zx injector fan also points to the center

injectors.

Injector heat shield - Jeep Wrangler Forum

[hr369]

megasquirt owners also deal with heat soak. someone suggested that the heat affects the copper windings inside the injector and reduces its pulse.

for megasquirt owners there are no options? they do have MAT air density correction but it doesn't seem to help the

problem much. would increasing pulse width during hot startups help solve the problem?

will len's hellfire be able to compensate using software?

M54 Megasquirt 3: Fuel Injector Heat soak

Edited April 14, 2014 by hr369

[ZXR616]

I've owned ZX's since 1979. I've never experienced the problem described. I live in Georgia where 100+ days are common.

Mine: 1979 280ZX 2+2 bone stock

1979 280ZXR with mega-squirt, header, cold air intake, 60mm TB, JSK fuel rail, electric fans

[rossiz]

...I'm not sure that's the typical heat-soak problem. It doesn't usually wipe out all of the injectors, just a few. The engine starts but runs bad. Yours didn't start all. That seems more electronic or electrical. Then when it did start you said it ran rough for a moment. Heat-soak running seems like eternity although it's only 20-30 seconds. But, if you do have it, it will come back, and you'll get familiar.

ok, been away for the weekend so couldn't post about the "friday fiasco" until now...

family trip involving a ferry (read as: can't be late) and i run a few errands for work, the day is sunny and 60's, last stop at an office for 20 min. while the z sits out in the sun. i come out and it does the typical dance: tiny "almost start" and immediate die, then NOTHING - no amount of cranking even gets a pop. i pop the hood and let it sit for a full 20 min. and still nothing. the manifold is still hot, but not excessively so - i can put my hand on it by the injectors.

i'm about to make my family late, so i call my son to come rescue me in the truck. he arrives with my tools, i pull all the plugs - they are bone dry, not a hint of fuel - deposits are all a nice mocha. i crank the engine w/the plugs out to blow out some air, then put in the plugs and it fires right up.

unfortunately this nonsense makes us miss our ferry and the vacation is delayed - anniversary, i'm in the doghouse. mighty pissed off.

while this doesn't seem to be the "classic hot-start" issue, i'm not sure WHAT my z's problem is, but it DOES seem to be directly related to heat soak - seems to be happening every time i have the typical situation: hot car, 10-20 min. sit, then problem starting, then starts when it cools down.

i've got to get this figured out, as the car is next to useless if i can't depend on it to start without a half hour of nonsense every time it's hot. do i really have to spend $1,000 on headers, fuel rail, injectors and revised exhaust just to have a car that will start regularly?!?

ugh.

if it weren't such a cool car, i'd have kicked it to the curb already.

[dbcjmc]

My '77 is stock except for K&N air filter and cold air intake, and I have exactly the same problem as rossiz describes. In fact, last time out, the car just quit at a stop light and I had to have it towed home. No Son with truck and tools to come to my rescue.

So reading thru here, the possible fixes are '79 fuel injector fan, '79 fuel rail, after market header, or fuel accumulator. Guess I'll start with the first one and see if that solves the problem.

[Zed Head]

These last few posts are interesting (although painful to read in rossiz's case). ZXR616 has a header, as does siteunseen, the only two cases of "no problem" so far. ZXR616's case is a little bit confounded by the fans, but they probably don't run when the car is parked (do they?).

I do things to my car that I wouldn't normally recommend to others, although the experiments are typically hidden so the car still looks good, but in this case I'll just describe my ugliness. If you get desperate to just know that the problem might have a solution, go to the wrecking yard and get 2 heat riser tubes from an 80s - 90s Chevy S10. It's a flexible fiber/foil tube that fits perfectly over the nose of the ZX fan. Get a one hour bathroom fan timer from Home Depot. GE brand. Get a ZX blower, or a marine bilge blower (Amazon). Mount the blower somewhere in the engine compartment, tape the tubes together to give the length to go from blower to injectors, punch sizable holes in them over the injectors, mount, attach and wire everything together. The purpose is clear so details aren't necessary. The tube will lay down right on top of the engine, the hardest part is squeezing it between the hood latch and the valve cove. But it's flexible. The timer is attached to the steering column. I reach down and turn it on whenever I park.

I used a lot of zip ties for my experiment, which is still there because it works so well. I have noticed though, recently, that I get a little stumble sometimes, even with the fan on. I wouldn't be surprised if gasoline formulations are changing. But if I forget to turn the fan on, it's a guarantee that I'll have a serious heat-soak problem.

On the stock ZX fan setup - apparently the ZX fans don't turn on much using the water temperature switch. Better to use a manual timer.

[hr369]

ZXR616, I think the fuel regulator, header and possibly megasquirt are the reason you don't get heat soak. Have you tweaked your MAT values or cranking pulsewidth in megasquirt ?

edit: from the mazda megasquirt forums

"i have upped my cranking pulses 30% to accomodate the e85"

Edited April 14, 2014 by hr369

[rossiz]

at this point the z is officially downgraded from DD to "toy" status, as i can't count on it to actually fire up when i need it. currently sittling in a coffee shop killing however much time it will take for the thing to decide it's cool enough to start again.

the thing that has me perplexed is that while i'm having no-start issues for sure every time it's hot, it's also been hard to start a few other times when it WASN'T hot, so i'm not convinced that heat soak is my only problem. i'll try to lay out the symptoms and maybe some sage advice can come my way.

it has three distinct starting modes:

mode #1 - starts right up, immediately and runs great.

mode #1.5 - gives a quick fire at first crank, then dies immediately and needs a great deal of continued cranking until it starts, then it runs just fine.

mode #2 - gives a quick fire at first crank, then dies immediately and WILL NOT START no matter what, for 1/2 hr. or so - not even a pop, nothing.

#1 is the norm first thing in the morning, but i've recently had #1.5 happen a couple of times first thing on a cold motor, and last night on a fairly cold motor. it started fine, i then drove a mile up the road to pick up my daughter and came back out and it was a #1.5 while humiliated teen sighed and rolled her eyes with embarrassment.

just now, the engine was hot, it's a sunny, mid-60's afternoon, i stopped at the hardware store for 10 min. and then the z gave a big fat #2 with NO start whatsoever. yes, the #2 moniker is a concious refernce to what it feels like to sit there wondering if i'm going to get home/to work/that meeting/etc. or not. i took out the plugs and they are all bone dry, which tells me i'm not getting any fuel. my pressure guage is between the filter and the rail and measures almost 40psi when i'm cranking or when i pull the solenoid wire off the starter and run the fuel pump w/the key to try and prime in more cool fuel.

it seems like the injectors just refuse to open at all. could this be an electrical issue?? the odd thing is how it runs perfectly whenever it runs - just has this starting issue. is there a different control for firing the injectors during cranking vs. when it's running (like the fuel pump relay logic)??

i am completely flummoxed...

help.

Edited April 15, 2014 by rossiz

[Zed Head]

As noted earlier, it doesn't really sound like the "heat-soak" problem. The fact you don't even get a pop sounds more like a spark issue. Are you still using the stock ignition module? With the ballast resistor? Next time, or right now, you might check for spark to be sure it's actually a fueling problem.