'88 TBI 350 - multiple personalities

[brendo613]

Hey all - drove the van today. Weeeooo! Happy as a clam. 2200rpm stall speed & lockup in 3rd & 4th are awesome features for a big rectangle cruiser like this van is. It sure acts best when warm, though. I think that's because it idles lower, which changes the apparent transmission behavior. I'm tempted to try new TV cable settings, but I might just leave well enough alone. I'm leery of getting that thing set wrong.

I'd like to add a tach to the van - any recommendations? Best price for a small, analogue gauge is $24 on eBay.

 

[Jims86]

Hey all - drove the van today. Weeeooo! Happy as a clam. 2200rpm stall speed & lockup in 3rd & 4th are awesome features for a big rectangle cruiser like this van is. It sure acts best when warm, though. I think that's because it idles lower, which changes the apparent transmission behavior. I'm tempted to try new TV cable settings, but I might just leave well enough alone. I'm leery of getting that thing set wrong.

I'd like to add a tach to the van - any recommendations? Best price for a small, analogue gauge is $24 on eBay.

I dunno about a tach, but just do the setting on that TV cable the prescribed way, and leave it alone. I get shivers down me back, just thinking about the results of a mis adjusted cable!

 

[MrMarty51]

K~00~l

 

[brendo613]

D'oh! High idle problem resurfaced during today's cold start, which results in late shifts & a slam when put in drive or reverse. I wonder what is making the engine idle so high. New IACV, CTS, clean engine grounds. I've got some investigating to do. Tips? Remember it's intermittent.

 

[Jims86]

D'oh! High idle problem resurfaced during today's cold start, which results in late shifts & a slam when put in drive or reverse. I wonder what is making the engine idle so high. New IACV, CTS, clean engine grounds. I've got some investigating to do. Tips? Remember it's intermittent.

hmmm. only cold. I would say vac leak, that is sealing up when things warm up and start to expand. Get a wrench and give everything a little snug from the intake manifold on up.. Then maybe do the Idle re learn proceedures. I have seen cold idles at 1100 rpm normally.
Also while its col, give the throttle shaft a shake vertcally and back and forth...there should be very little play....its more of a problem on manuals, but depending on your mileage, it may be a factor.

 

[brendo613]

Good theory, but from its behavior this is definitely ECM controlled - after a couple mins, AIR injecton starts pumpin, and the idle lowers. Trans slam disappears with normal idle. For the hell of it, I carb cleaner spray-tested for a vac leak & it's all tight. Throttle shaft is tight, too. TPS measures 4.98 VDC key on engine off; the blue middle wire ranges from 0.55 VDC to 4.15 VDC. TPS reads fine after several testings, both before and after high idle problem was observed.

No relevant trouble codes either (old stored ones are being cleared now). When does the computer allow fuel vapors to be sucked back in? Maybe the canister or purga valve are malfunctioning / leaking when that system is activated. All other vacuum lines are tight; gotta vacuum-test canister tomorrow. Getting cold and dark here.

 

[brendo613]

Also, when I reset ign. timing (new dizzy installed), the timing was jumping around by a few degrees. Attributed it to nothing worrisome, until now. Single-wire connector below dizzy was disconnected for the ign. timing reset.

 

[89Suburban]

Also, when I reset ign. timing (new dizzy installed), the timing was jumping around by a few degrees. Attributed it to nothing worrisome, until now. Single-wire connector below dizzy was disconnected for the ign. timing reset.

Man how did I miss this. Welcome aboard neighbor!

I am in King of Prussia.

 

[bucket]

Swims didnt have his done, I think he just soaked them. Its very rare that a tBI injector ever really takes a ****....most cases I have seen, are where the truck sits for a long time.

That's my experience too. The ones that completely fail are ones that have sat for a while.

Also, when I reset ign. timing (new dizzy installed), the timing was jumping around by a few degrees. Attributed it to nothing worrisome, until now. Single-wire connector below dizzy was disconnected for the ign. timing reset.

Is it a new drive gear on the dizzy? What did you set the timing for? I like 6-10 degrees advanced.

 

[brendo613]

Paw Paw - thanks for the welcome. A local GM comrade - most excellent

Andy - new drive gear indeed. Much nicer than old unit. The 350 never felt so tight & responsive since I've owned it. As per the underhood emissions sticker, with the tan / bk wire disconnected, I set the timing to 0 degrees. Maybe only a few years call for that? I'd seen 6-10 deg. mentioned elsewhere.

Curious note: engine starts best after ignition has been turned to on for a second or two. SES light blinks, then there's a click from some solenoid / relay. If I start the vehicle after this point, I'm apparently guaranteed a strong & surefire startup, with no hiccups. Sometimes it backfires through the intake if I throttle it, key-turned-to-start right away. It sounds like it's about to burn my starter out too, by catching somewhat, stumbling, then starting for real. So, I prefer to wait a second or two @ the on position before starting

Also, I haven't had the random high idle since Friday. Of course, I've been trying to get it to ... I keep the ALDL jumper handy in case I need to jumper pins A & B to reseat the IAC pintle. It's a last ditch effort, which I challenge the efficacy of - but I intend to try SOME high-idle-evading attempt come the next time it appears. PCM grounds @ thermostat are clean & TPS, IAC, injector, etc. connectors are dieletric greased / siliconed up.

 

[bucket]

Yeah they call for 0 degrees, but I find they always like a little more timing.

 

[MrMarty51]

I do`nt know if it helps, but, I set the timing on My TBI engine to 2* advance. figure I can cheat on that system without anyone getting harmed, and, I do`nt have to go and make amends to anyone either. LOL

 

[MrMarty51]

turning key to on and waiting for that two or so seconds lets the fuel pump run and build fuel pressure before the engine is cranked over.

 

[MrMarty51]

By posting infurmation in several posts, i can be a post ******* and gain in My post counts toooo. LOLOLOLOLOL

 

[Jims86]

Brendo, Vac leaks can also appear under the intake. To check, plug the pcv line to the air cleaner, take out the pcv valve, plug the valve cover, and plug the pcv line with a bolt or dowel.
Remove the dipstick, and using a propane torch(with the burner tip removed, and a piece of 3/8 fuel line stuck on it) connect it to the dipstick tube. Start the van, let the idle settle in, and turn the propane on. This will fill the crank case, reaching up to the underside gaskets of the manifold.

Vac leaks with TBI, or any speed density EFI, will usually cause a higher than normal idle. speed density adds fuel, due to the percieved lower vacuum at the MAP sensor, and extra O2 at the O2 sensor.

Mass Airflow meter equipped vehicles, like Carbed vehicles, will run rough, and lean, Because a vac leak is un metered air, that the MAF sensor/ Carburetor does not see.
As far as the Evap cannister, there is no computer control of that until about mid 1993, when the newer PCM controlled TBI with the Electronic transmissions.
Your van should just have a vacuum line going to the Throttle body, on the medium sized ported Vacuum nipple.