sparkyy

Hi, my name is Mike and I broke my lt5....I also have an lt4 which I work on including a installing a new oti,.... my point is I know just enough to get myself in trouble. When I bought the zr1 it seemed a little sluggish so I did the works, injectors, coils, plugs. I discovered that the vacuum pump in the front was frozen so I replaced it and....whallah!...the secondaries worked like a charm. Pure genius, right?? So I put it all together and it barley started, missed horribly and blew white, very rich smelling smoke......anyway, I've tried everything...put the old coils back in, even tried the old injectors....I've become an expert at plenum pulling. The electrical connections are pretty much idiot proof and I've triple checked the plug wire routing. Its acts like an old carberated engine with a stuck needle valve …….I'm stumped, any help would appreciated thanks , Mike

Crabs

Mike:
Hate to ask the obvious, did you forget to hook up the MAP sensor vacuum line?
It's the one under the back of the plenum next to the PVC valves and piping.
With that one off it'll run like crap and blow smoke.
You might want to check the plug at the back of the DIS module, if any of the pins are bent (and it's easy to do, just ask me know I know), it'll do similar.
Failing all this, where are you?
Maybe one of our members is local enough to drop in and do a little armchair diagnosis.

'Crabs
'90ZR1 #792

Dynomite

Did you drain coolant when you removed Plenum...white smoke is coolant. Who is to say what you missed when you put it back together.....bent pins, wrong fire order, pinched wire...….could be anything.....which means...check everything one more time.

When you do get it running.....hold your hand on the two coolant manifolds to make sure they are getting warm within a minute or two which assures coolant is flowing properly. The coolant manifolds attached to each injector housing each side of plenum. You do not want an air locked water pump.

Sljs3413

Check the pcv system, hoses get soft as butter, check map sensor. Did you get the new plenum gasket on correctly?

Sljs3413

Could you have got the wires mixed up?

sparkyy

I did not drain the plenum...is it possible that some coolant went down the inlet? If this could be my problem it gets better, I pulled the plenum at least 4 times, each time possibly leaking a little more down the pipes...what can I do other than remove the plugs let them "air dry" don,t know if that works...I checked for bent pins, all vacuum lines... I'm almost certain that all the connections are correct....here we go again

Dynomite

YES...……..You have to drain the radiator below the level of the injector housings or coolant will get into open cylinders when you remove the Plenum....YES...….
That was probably the white smoke. Pull plugs and turn over the engine several times. See if any coolant is pushed out. Then replace plugs and fire it up again.

But if the engine actually ran you do not have a water lock in the cylinders and the white smoke should go away in a minute or two. Just fire the engine up without having to remove the Plugs. But....Then......do make sure you have coolant flow by making sure those coolant manifolds get warm within a minute or two. If they stay cool...…..there are all sorts of ways to remedy.....

Coolant comes from the TB coolant port between the front two plenum runners on both sides of the engine.
Coolant would go into an Injector Housing Port and if not an open valve, coolant would fall into the cylinder as you start the engine.
Then lots of white smoke and rough running for a few minutes if not Hydro locked.
I have TB coolant blocked at the Injector Housings on all Zs but that is a different topic.

left click my signature (LT5 modifications/Rebuild Tricks)
and go to page two...….

ENGINE COOLING
Post 7 - Thermostats, Fans, Water Pump, and Radiators
Post 8 - LT5 Radiator and Initial Coolant Fill Tricks
Post 9 - HVAC Temperature Display And Radiator Efficiency Test Runs
Post 10 - Water Pump, Coolant Temperatures, and Coolant
Post 11 - Radiator Debris Screens
Post 12 - Getting The Air Out of the Coolant System
Post 13 - TB Coolant Discussion
Post 14 - Coolant Characteristics (Mix, Pressure, Elevation)
Post - Eliminated TB Coolant Photos and Details

DDSLT5

Always drain plenum first. Check the map sensor connection.

FASTAZU

I would have to agree with the bent pin or lose pin in one of the connectors.

Aaron71771

When pulling the plenum, drain a gallon of coolant out the bottom of the radiator. The drain plug is in front of the passenger side tire. I use a milk jug. Helps so you don't get coolant into the intake. Pull the plenum again and check, recheck the connections and the plug wires. Look into the connectors and make sure they are good. As suggested check the DIS plug for a bent or pushed out pin. Recheck your plug gaps. Check the resistance on your injectors. Check MAP hoses for vacumn, also check your PCV hoses and valves.

Marc Heibeck has an under plenum service DVD for $50. Lots of good info on there.

sparkyy

Thanks to everyone, this thing has my head spinning. I'll try,try again until I find the problem, we all know that it's something silly , but i'll post the solution when I find it thanks

Dynomite

You can see here the red allen head plug (TB Coolant Path) and if the gasket around this area is leaking you get coolant into the adjacent injector housing ports (if not plugged with Allen Head Plug). In your case, if you did not break the Plenum Gasket in this area you should be able to just run the engine (since it started already and just run rough but with white smoke) and burn off any additional coolant in the Injector housing or cylinders in question within a few minutes. Once you get rid of the moisture the engine should smooth out.

I would pull the plugs on cylinders 1,2,3 and 4 to make sure you have not blown a Plenum gasket first. Pulling the plugs on 1,2,3, and 4 is the easiest of the 8 plugs and should only take a few minutes.

The only thing that causes sweet white smoke is antifreeze coolant

Jerry’s Gaskets Has all the gaskets including the Plenum gaskets (I use 1/32") you would need.

darklordftt

We were worried about breaking the radiator drain plug on mine when we pulled the plenum. I siphoned all of the coolant out of the tank near the passenger firewall. I believe this also caused the coolant to drain from the intake, as I had no issues after re-installing everything after doing the injectors. The DVD Marc sells also points out other bolts and locations to inspect and tighten to prevent future oil and vacuum leaks. It's worth the money.