Engine surges then stalls...

[Quad4Z26]

So my car surges then stalls, im thinking it has to do with vac lines. If i leave one vac port on the throttle body unplugged itll idle and not stall.

Need help routing vacuum lines to the fpr, map and the purge solenoids at the bottom of the coil pack assembly. Also since i have a 3500 upper intake manifold and lx5 throttle body....there is some vac ports on the throttle body that if i leave unplugged the car will idle 900-1000rpms with small surges but will not stall. I took it out for a spin with the small port on the side of the throttle body unplugged and usually stays above 2krpm while driving, will only idle at 1k at a complete stop. Did not stall.

Any help/tips appreciated!

[Rettax3]

I don't know if you have a write-up on your engine-swap or not, so it is hard to say. What ECM/wiring are you using? '96+ OBD2 that uses a MAF, or is it strictly speed-density MAP controlled? Is it a full-on 3500 swap including all wiring, injectors, ECM, etc? Generally speaking, a vacuum-leak can best be found with a can of ether or starting-fluid, spraying at various parts of the engine until you find a spot that causes a surge in RPMs. Remember that the car needs a vacuum-line for the HVAC controls, and should have a vacuum-accumulator (IDK where it is on a '94, but my '95 Z-26 had a round 'ball' accumulator below the left headlight, IIRC. Did you keep the 5-speed, or swap to an auto? The later four-speed autos also need a vacuum-line to the modulator on the front of the tranny. If your 3500 is being run by its' original ECM that is still looking for an auto tranny (did the 3500s ever come attached to a manual tranny?), your idle might always be a little weird, unless you can get the ECM flashed for the swap -I have a little idle-oddity on my 3800 Beretta, but it is very minor and barely noticeable. Aside from that, I would suggest plugging everything except for the MAP sensor and FPR until you are sure you have no leaks and the idle-speed issue is fixed, then worry about the emissions crap later. Good luck, pics are essential, unless you already have them posted (then please direct me to them ).

[Quad4Z26]

Full 3500 engine with lx5 tb 5spd, all controlled by a 96 L-Body engine harness.

Not that i really care of the emission equipment but i figured that it might need it to run properly...

[Rettax3]

Sounds like a great car. I still want to see pictures! So are you running a 3500 with 3100 injectors and ECM, or 3500 injectors on a 3100 ECM? Either of these mismatches could cause driveability issues, lean or rich run conditions that could mess with idle speeds... Or did you figure out how to run a 3500 computer through the L-body harness? Is your computer from a five-speed car?

[Quad4Z26]

Harness was from an auto car, running 3.4DOHC injectors which should be 24# just like stock 3500 injectors iirc.

Running stock computer, have a 97 ecm that i just received that im going to ship to 3x00-Modified so he can flash it with proper settings.

[3X00-Modified]

Well first off your trying to run the stock ecu on those injectors... It wont be happy no matter how you slice it. The IFR is setup for 17lb injectors. I know if I put the stock IFR on mine the car wont even start because it floods the crap out of it and it can't correct enough to lessen the amount of fuel delivered. Probably why it will idle with a vac leak because your making it leaner.

I can't stress enough to people, when you make radical changes to fuel or air delivery you NEED to get the ECU updated otherwise you'll just be chasing problem after problem that you can't solve because the ECU has NO idea what it's working with.

[Quad4Z26]

Well first off your trying to run the stock ecu on those injectors... It wont be happy no matter how you slice it. The IFR is setup for 17lb injectors. I know if I put the stock IFR on mine the car wont even start because it floods the crap out of it and it can't correct enough to lessen the amount of fuel delivered. Probably why it will idle with a vac leak because your making it leaner.

I can't stress enough to people, when you make radical changes to fuel or air delivery you NEED to get the ECU updated otherwise you'll just be chasing problem after problem that you can't solve because the ECU has NO idea what it's working with.

I need to send you my spare 97 ecu. I sent you a PM.
IFR?

[Money pit Beretta]

Infrared Receiver.

[Rettax3]

Infrared Receiver.

Shame on you, Money Pit! IFR stands for "Instrument Flight Rules" for most, or "I Follow Roads", if you have to calculate the weight of mud and hay-seed into your weight and balance figures!

[3X00-Modified]

Injector flow rate

[Money pit Beretta]

Infrared Receiver.

Shame on you, Money Pit! IFR stands for "Instrument Flight Rules" for most, or "I Follow Roads", if you have to calculate the weight of mud and hay-seed into your weight and balance figures!

I had to pick one, it was a toss up. I picked that because it's more in the lines of what 3X00 does for a living.

[3X00-Modified]

Well what better fits what I get told all day is "Internet F-ed up Royally..."

[Money pit Beretta]

That sounds about right.

[Quad4Z26]

Found my OBD2 scanner, since my SES light was on I assumed it was the tranny codes setting it off. Found codes that had to do with the oxygen sensor (no data received)

Went to local auto parts store and brought home an oxygen sensor. Put it in, car idled a little weird for a few seconds then smoothed out and DID NOT STALL. Took it out for a spin and ran good. (still sending my ECM to 3x00-modified)

Now for another question, where does this little hose go? It comes out of the engine harness but I have no idea where it goes!

Heres some pics

[Money pit Beretta]

Looks like the vacuum hose that goes to the inside to run the HVAC.