JamesWade2002

Okay, so here is the saga thus far. I have two of these cars..first one is an 86 with a good motor. All of my previous posts have been about this car which we just found out had a high impedence injector for one of the primaries..so problem solved, I thought. Now that motor has been swaped into an 88 chassis with the original high impedence injectors installed on the 88's harness. when everything went back together, the car ran great for one day. Then while on the way to work, I shifted to 4th, when to 5,000 RPM and then just hit a wall. The tach stopped, the engine bogged, and the exhaust noise made this funny sound like it lost all of its tinny-ness. Mr. Bob86 and I checked all of the wiring and grounds. all grounds had good continuity, so I made some more anyway. We tried different injectors, checked voltage at the secondaries...changed secondary injector wire conectors to the injectors... he wired the injectors to the ECU...still no top end. The grounds seem to help and the car seems to run nicely up to that point. sometimes when it is cold outside, the car will pull in first gear. It will rev out under very light throttle. As you go through the gears, the lower your new redline gets with less and less load on the engine being tolerated. its like having a 95 MPH speed limiter. I just pulled the secondary rail off. there was fuel pressure to it. The pintle caps on the injectors had fuel and oil on them (I premix). I am running no emission equipment of any kind. Header, straight pipe, muffler. K&N cone...ported manifolds...car likes to flood..probably need injectors cleaned....new solid core plug wires. NGK plugs were cleaned with media blaster when we checked everything over the weekend. totally stumped here.

JamesWade2002

oh and forgot about the car liking to rev in first gear when its cold...but only like once.. only when the car is cold and the weather seems cold...like when I get off work early in the morning. as soon as you let it warm even a little, you can forget even half throttle past about 3800 rpm. We tried some equally leaky but functional 550cc injectors off of MRbob's TII. this did nothing.

WAYNE88N/A

My two "walls" in history were caused by:
1) clogged pre-cat (I know, you don't have)
2) clogged in-tank inlet filter

Something to check, anyway

JamesWade2002

checked intank prefilter and flowed soapy water through the pump. it flowed fine. and yes no cat. anyone else?? Any other ideas? Thanks all!

Sesshoumaru

iTrader: (1)

disconnect your alt wires and try it with only your batt.

JamesWade2002

why would that do anything?
Does anyone know if I can swap an earlier ECU from an 86 into my 88? Could anything else be causing this? AFM bad? Whats troubling me about this is that the problem happened suddenly. It was very strange. The car still revs smooth below 4,000 and will still rev with light throttle so I am assuming it has good compression. I'll check that tomarrow. I usually run around 100:1 ratio on my premix, and I only use TCW3 rated stuff so I don't see it clocking in my secondaries, plus it came on so fast and then got worse within 30 miles. Then I regrounded the ECU even though it was not needed, and it got a little better.wierd!

Sesshoumaru

iTrader: (1)

had a car that didn't got past 4-5k. rev smooth below 4k.

varried a couple hundreded each time but back fired bad and just wouldn't climb past 5k EVER.

voltage at idle was 14.4volts.

disconnect alt - it ran fine.


do whatever though-

as long as the first two numbers are the same u can swap ecu's

J-Rat

iTrader: (2)

Okay, Do a few things for me here.

#1: Disconnect your pressure sensor. Go for a drive.
#2: Scan for codes http://www.teamfc3s.org/info/article...odes/main.html

Rat

JamesWade2002

I diconnected the pressure sensor and the car ran no different except the "wall" at 4K was exactly at 3800 and was very hard, like a rev limiter. it is not that hard normaly. perhaps I have a bad pressure sensor?

87na

iTrader: (-1)

My car did the EXACT same thing. Its not getting enough fuel, thats why when you lightly press the pedal it will rev, its getting a good a/f ratio. thats why when you go wideo open it works for so many rpm and they sputters out with the secondaries. You just need to figure out why its not getting enough fuel.

I would recomend:

1. Rarely looked @ is the fuel pump ground, those tanks get really dirty sometimes
2. Im suprised no1 said this yet but um a fuel filter, mine just had a ball of rust in it from sitting only 2 months. So i just bought a autozone see through generic one and it worked better then the original

J-Rat

iTrader: (2)

No one has mentioned it, because none of that stuff will cause a magic wall at about 3800 rpm...

REconnect the pressure sensor, leave the vac line off. Dont cap the pressure sensor, but cap the one going to the motor. Report back.

HAILERS

YOu know where it says in the manual to remove the boost sensors vac line and plug the line.....and how the secondary injectors will fire each and every time you reach 3500 (3500) rpm????? and how you can listen/feel the secondary injectors firing??????? And how the secondary injectors are the ones just below the inlet duct and are easy to access to do this??? Yep. I thought you'd remember. So go out and do that and see if they are working or not. And are You sure the injectors are approx 12ohms. Easy to check the secondaries.

WAYNE88N/A

Ha ha, I just tried this yesterday, Hailers, and thought my secondaries weren't working (hadn't kicked the rebuild in until yesterday- thought for sure they had to be working since 4th gear took me up to 110 pretty damn fast) ,and I used an actual stethoscope & still heard no "clicks"...so the books are wrong? Finally hooked the 'ole meter up to the secondary outputs at the ECU & took her for a spin...They're definetly working, reaching about 50% duty cycle during the romp...

HAILERS

Yeah, that *hear the injectors click* is either BS or wer'e bad on hearing, one. A meter is proof positive. I'd suggest that to WADE2002...the meter that is.

WAYNE88N/A

Actually, if you think about it, how could disconnecting the boost sensor cause the secondaries to come on at ANY rpm? The ECU needs to see a certain pressure (exactly what it is, I dunno) from that sensor before it'll let 'em kick in, in the first place...That brings up something else I was thinking about yesterday- what does the ECU use internally for its tach signal? There is no external tach feed going in, so is it using the CAS signal(s)? The igniter/coil triggering outputs?

J-Rat

iTrader: (2)

Because if you disconnect the vac line from the pressure sensor, and cap it. It sees "0" vacuum (or ambient). And it "SHOULD" allow the secondaries to turn on.

WAYNE88N/A

I know what you're saying, J-Rat, but I'm tellin ya, they weren't clicking above 3800 during that FSM (or Haynes) test, and like I said, I even had a stethoscope on 'em...Further proof was connecting the meter at the ECU with the boost sensor line off, they stayed at 14v the whole time, throughout the rpm range (well, up to about 5k, anyway)

White 87 13B

This is very interesting...keep going! This is addressing one of my issues...That Stutter...Fuel Cut, Thing...Haha Keep going!

WAYNE88N/A

Ha ha, don't get too excited- we're talking about secondaries that work normally, but don't TEST normally per the manuals...I'm with Hailers- the only sure-fire way to see what the secondaries are doing (or not doing) is to keep a meter lead (or small wire w/ clips to lead) on the ECU pins (3F & 3H on an S4), and take the car for a drive...If it's still reading 14v or so and you're on it above 4,000 rpms, they 'aint working...

Don't want to confuse 'yall- that's pin 3F to ground, then 3H to ground...sorry...

White 87 13B

NO...Thanks! Actually I was curious to if that could be my 3800-4000 rpm problem...the car starts jolting back and forth! Like it's missing...not getting fuel or air...so this is interesting!

WAYNE88N/A

In that scenario, with the pos meter lead to pin 3F (3H for the other one), and the neg to ground (the stud sticking up near the ECU works well), you should see the meter start going down from about 14v, then all of a sudden jump back up to it...That would be the secondary kicking in, then kicking back off for some reason...Do you still have the little "restrictor pill" in the vac line going to the boost/pressure sensor? It's usually near the intake end of the line...Could just be dirty/insufficient grounds, though...

JamesWade2002

I don't have and have not had a restrictor pill in the vac tube from pressure sensor to intake ever... the car ran fine.. then it suddenly hit this wall... since adding grounds and cleaning fuel filter..said wall has gotten fuzzy but is still there, it just moves. I am sick of injectors and wires and associated BS. Does anyone have a 6-port to holley manifold for sale? If I let the pressure sensor read 0 vacume and it works, does that mean I have a bad pressure sensor?

Sesshoumaru

iTrader: (1)

what is the voltage at idle

HAILERS

The seconday voltage should read battery voltage at idle and on the whole stay at that figure until you hit 3500 rpm. If the vac hose is off the boost/pressure sensor, then the voltage should start to drop at anything over 3500 rpm . It'll be noticable and if your really on it drop into the seven or lower voltage. Sorry, have not done this in a while.

Ain't there, ain't heard the car run......but it sounds like the drivers for the secondary are not putting out. You won't know til you do the test mentioned above. Use a meter. You should be able to see this happen in the driveway. Note: the voltage will drop a lot lower if on the street. Come to think of it....I know it should drop by reving in the driveway, but don't expect seven or lower in the driveway.

JamesWade2002

okay what if the connector reads 12 when you first turn the key to the on position before starting the car and then it slowly drops to 0 over a few seconds?