88 4.3 keeps stalling, any suggestions?
 

1988 S-10 Blazer, 4.3, TBI, 4WD, bought used in 6/94 and still have it. (How long do people keep these things anyway? People look at me like I'm nuts when I tell them I've owned the same car for 16 years.) It's been my backup since I got the 99 Blazer back in 2003, but that one's laid up at the moment (see the Pre-Cat thread in the Gen2 forum) so I've been driving the 88. It's got about 208K miles on it at the moment.

There's been a long-term problem with stalling when warm. I mean years, there was a period when my dad was driving it and he noticed it as well. Problem is, lately it's geting worse; when it started happening, it was only after a long highway drive, it would start shaking and die when you get to the bottom of the off-ramp. Now it's happening more often at what seems to be random times. Worst part is, there's no code being set.

Thus far I have replaced:

▪ MAP sensor (threw a code)
▪ EGR vacuum switch (likewise)
▪ Spark plugs (took out Bosch double platinum, put in Delco Rapidfires)
▪ Spark plug wires
▪ Cap & rotor (see below for a funny story)
▪ Coil
▪ Most of the rubber hosing that I could reach under the hood
▪ IAC motor
▪ EGR valve (found it was jammed halfway open; mechanic did this one)
▪ Fuel filter (and was that an adventure, getting it out after it's been in there since '01. Mechanic refused to touch it, so did the Chevy dealer, so I had to do it myself)
▪ Gas tank (was rusted out & leaking, also replaced by mechanic, along with-- )
▪ Fuel pump (last replaced in 1995) and sock, and
▪ Fuel sending unit
▪ Windshield wiper motor (OK, that had nothing to do with it, I know)
▪ Possibly other stuff that I've forgotten, this has been going on for 2 years now

Still stalling.

I've browsed the threads on here, and it's been suggested that a bad TPS will tell the ECM that throttle is closed when it's not, and the ECM will shut down fuel delivery. So I've got one on order from that online bookstore (local NAPA joint had it in stock for $82, the bookstore wanted $25. Guess who got my business.) It should be getting here on Monday or Tuesday and I'll stick it in and see if that helps. If not, what's my next step? Fuel pressure regulator maybe? Seafoam? New ECM/PROM? Waving a dead chicken over the TBI? (Just kidding on that last, but only just.)

I'm open to suggestions. Thanks in advance.

(Oh, the funny story. I went to Strauss for the cap/rotor because they were around the corner from my house so I could walk there. The one they sold me didn't fit: I had screws, the one they gave me had retainers. I brought it back and told them it was wrong, and they said it must be correct because their computer said so. :icon_no: I showed them the one I'd taken off, and they told me that someone must have taken a distributor out of some other kind of car and installed it in my truck. http://www.customerssuck.com/board/i...milies/wtf.gif I finally gave up, got on my bike and rode to a different Strauss. The cap & rotor they sold me was in the exact same box as the first, but what do you know, the cap inside the box actually resembled the one on my truck. It was more logical to the staff at the first store that I had the wrong distributor in my truck, than that they had the wrong part in the box. That store eventually closed down, and I can't say I'm all that surprised; I never got out of there without pulling my hair out, and I can't have been the only one.)

Replaced TPS. No change. Now what?

(%^%*^&* designers. They used a T-25 screw head in a place where you have no room to put in a socket with a torx driver. WTF is wrong with a hex head bolt like every other one on the car? So I went to the Autozone and picked up a set of torx angle wrenches. Got one screw out fine, the other one stripped out like it was aluminum (which it isn't, I checked it with a magnet). Got out the ol Vice Grip, it came out about two turns and pressto, the head snaps off. Removed the switch, sprayed some PB Blaster on the remainder of the screw, very carefully turned it out with the vice grips, and you guessed it, it came out another two turns and snapped off. And I didn't put any side pressure on it either, you could see where it had twisted in the middle. So now the new switch is held on with only one screw, I hope that doesn't come back to bite me in the ass. I really should take out the whole throttle body, drill out the remains of the screw and put a Helicoil in there, but that's not something I feel capable of doing at this point.)

I would suggest that you get a TBI rebuild kit (NAPPA). Carb cleaner solvent (NAPPA) and totally clean and re-assemble the TBI unit. While it is off you can fix the broken screw. Could be that you have a port partially clogged. Looks like you changed all the parts that I would suspect. I would suspect EGR valve first since it does it when it is warm up. The engine is in closed loop operation which means that the egr should be functioning. This is also related to the O2 sensor. Next would have been the IAC but you have changed that as well. I would also make sure that the timing is set correctly. I rebuilt my TBI about 2 years ago and it made a huge difference. Do you know what your fuel pressure is? It needs to be about 11 psi. The kit will include a new pressure regulator spring and diagphram. When I rebuilt my TBI the port for the PCV Vacumn line was totally blocked and I did not have any crankcase ventilation and the pressure was blowing oil out of my dipstick tube if it was not fully seated. The pressure was also blowing out the PCV fitting from the valve cover.

make sure the port in the front of the TB where the PVC hose goes isn't clogged up, they get a lot of gunk in there and stop up, just drill and retap the screw for the TPS its not a high torque bolt so the aluminum will hold it just fine. second on rebuilding the TB, and check your timing with the wire disconnected under the dash.

Problem still not solved, but at least one side trip down a dead end has been resolved.

I finally got it to the mechanic while it was sputtering (it always worked fine in his presence: maybe it was scared of him or something). He looks around under the hood, says he hears vacuum leaking somewhere (no surprise there, I've replaced most of the hoses but there's probably still some rotted rubber that I haven't found yet), and suddenly sees something moving that shouldn't.

Him: Did you replace the spark plugs on this vehicle?
Me: Yeah, I did.
Him: Well, you did a terrible job. One of them is loose.
Me: How'd that happen? The book said to tighten them to 12 foot pounds, and that's what I set the torque wrench at.
Him: That's because you just go by the book, you don't have no common sense.:icon_angel: You also got burn marks on one of the wires because you didn't use any wire looms.
Me: I didn't have any.

Well I guess that would explain the ticking I'd been hearing recently. (I'd figured the exhaust manifold had cracked when we replaced the EGR valve.) I shut off the engine; he grabs the boot and unscrews the spark plug and the wire together, by hand. Now I did put on the anti-seize compound when I installed the plugs, but that's ridiculous. He puts the plug back, tightens it up and puts the wire back on. Started it back up and it ran. I've driven it about 140 miles since then and it hasn't stalled yet, but that's all highway mileage; we'll have to see how it does in the city. I still have to put it in neutral at stop lights. Next project I guess is to track down the vacuum leaks and check on that wire with the burn mark, also I think I'd better re-torque the other five plugs too, just in case. Once I have some other car to drive, I'll take off the TBI and mess with that, but I don't want to take the chance of leaving the car totally undriveable right now.

(Remember it was stalling even before I changed the plugs, so we're back to status quo ante, but that wasn't great to begin with.)

I find anything else, I'll update this thread.

Threw a half can of Seafoam in it tonight. Poured it through the throttle body real slow, so it didn't stall, then shut it down and dumped the rest in there. Then I closed it back up and went in to do my shopping. (I did this in the back parking lot of a Target, so's I wouldn't smoke up the neighborhood.)

Came back outside, started it up, and no smoke. I've seen the videos, and was expecting this huge cloud, but nothing. http://www.customerssuck.com/board/i...s/confused.gif

In any case I drove it home and it seems to be running a little smoother, also the idle speed has gone up a little bit. Another 140 mile round trip tomorrow, we'll see how it behaves.