I screwed up something, but what???

I'm just guessing, but you did ask for guesses. Something is wrong with the vacuum system. My old 1974 Dodge Dart had a vacuum hose from the carb to the air cleaner. Sometimes if I had the air cleaner off, I'd forget to reconnect the short (about four inch) hose. The car would run terribly.

I wonder if the intake manifold needed some kind of gasket sealant, when you put it back on? I'm really just guessing.

Christopher A. Young Learn more about Jesus

In another thread, I was talking about replacing my A/C evaporator and then replaced the intake manifold in my 94 Suburban. The truck ran excellent before I got my grubby little hands in there.

Now I replaced the manifold but the truck now runs like total garbage. It will start and seemed to start reasonably well but felt like it was running on 7 cylinders. But worse, it pops when I try to rev up the engine. It will speed up ok but I get a few pops, still feeling like it's running on 7 cylinders. [the pops are out the throttle body, not out the exhaust] But when I try to drive it, it runs like total garbage. Poor acceleration with lots of popping but it does eventually speed up, when it can catch some RPM. When trying to accelerate hard [to the floor] at about 40 kph, there is as LOT of very rapid popping and lousy acceleration. Sometimes it won't accelerate at all, sometimes it will. I set the timing exactly as it came out then I tried to vary it both ways with mixed results. Nothing was altered in any way from before. BUT I did notice one thing, the distributor shaft seems to have a lot of play. Probably needs to be replaced but the truck ran excellent with the distributor as it is.

Does any of this make sense to anybody?

I used Permatex gasket adhesive on all gaskets. I checked every vacuum line and they were all in place. Interestingly enough, the "service engine soon" light only turns on if I let it idle for a while and turns off when I drive it [which isn't easy right now].

On Wed, 6 Jun 2012 07:35:21 -0400, "Stormin Mormon" spake thusly:

My first thermostat replacement, I used Permatex I, rapid hardening. About an hour later, I was driving in a cloud of glycol steam. Find out I needed Permatex IIb, non hardening.

I'm at my limit of what to think about, and guess. A couple other folks on this list are far more skilled and wise than I am. They will be more help.

Christopher A. Young Learn more about Jesus

On Wed, 6 Jun 2012 07:35:21 -0400, "Stormin Mormon" spake thusly:

First off check the firing order. Double check the position of the rotor to make sure the distributor is in correctly, one tooth off can make a big difference. Take a close look at the EGR valve and make sure it is working and not stuck open.

On Wed, 06 Jun 2012 10:10:28 -0400, "Steve W." spake thusly:

Problem solved!!! You were on the right track with the firing order. I had #7 and #5 plug wires reversed on the distributor cap. That is what I get for working on the truck outside, in crappy weather, late in the evening, dog tired and hungry. :-)

They were probably reversed at the plugs, too. Better go back and swap the spark plug ends, too. (You realize I'm just teasing?)

Christopher A. Young Learn more about Jesus

Problem solved!!! You were on the right track with the firing order. I had #7 and #5 plug wires reversed on the distributor cap. That is what I get for working on the truck outside, in crappy weather, late in the evening, dog tired and hungry. :-)

Figured it would be firing order or a tooth off. They are the common oopses when dropping the dizzy in.

Thanks for the feedback. Lot's of folks never say if they got things straightened out or not.

I'm a retail repairman. You are so, so right.

Christopher A. Young Learn more about Jesus

Thanks for the feedback. Lot's of folks never say if they got things straightened out or not.

I answer questions on a few auto help sites and it's just interesting to see who says thanks or lets you know what the outcome was. It's not easy to answer some things when the description allows for 30 different problems and then the person gets P O'd when you ask for more specific items.

I guess some folks are just simply unreasonable? Glad I don't live with people like that!

Christopher A. Young Learn more about Jesus

I answer questions on a few auto help sites and it's just interesting to see who says thanks or lets you know what the outcome was. It's not easy to answer some things when the description allows for 30 different problems and then the person gets P O'd when you ask for more specific items.

I don't know if they are unreasonable or just think that one symptom they describe means only one solution. I get the same stuff in the shop now and again. Someone will come in and say "I had the code scanned, I need a XXXX" So I'll ask them what the code was and what the vehicle is actually doing. There are very few codes that actually point to one part as the problem, most simply tell you what the ECM is seeing as a problem. Something like a missfire on one cylinder could be a bad plug, bad C.O.P., bad wire/cap, bad injector, bad valve(s) and a few others. Trying to get people to understand this is the problem.

On Thu, 07 Jun 2012 09:35:47 -0400, "Steve W." spake thusly:

Kind of embarrassing for me, as I am a mechanic, altho not automotive. I work for an equipment rental company. I work on aerial boom lifts, tele-handlers, scissor lifts, skid steer loaders, generators, light towers, compressors, excavators, plate tampers, compactors and rollers. Most of what I see is diesel powered hydraulics.

You just looked past the problem. I have yet to find anyone in the trade who hasn't done that a few times. If they claim they never have then there are two possibilities. One - They are God/Jesus/Holy Spirit Two - They are a liar.

I know I've had a few times when a second set of eyes caught the problem, after I had spent an hour trying to track it down.

On Thu, 07 Jun 2012 22:26:14 -0400, "Steve W." spake thusly:

I spent 4 years as a service adviser at a boat dealer and at an RV dealer so I know exactly what you mean. You don't know "expensive" until you deal with outboards, especially Mercury. I had to order an ECU for a Mercury Optimax 225 HP outboard engine. Good thing it was a warranty repair, the retail on the ECU was $8700 Canadian funds. If I hadn't seen the invoice myself, I wouldn't have believed it.

People are never more impatient or unreasonable when it comes to their $20,000+ toys.

On Fri, 08 Jun 2012 00:55:38 -0400, "Steve W." spake thusly:

It was another mechanic where I work that figured it out immediately, without even seeing the truck, just based on my description. He was prepared to bet money on it. Once he said firing order, it made perfect sense to me.