Problems Accellerating 99 chevy suburban

I have a 99 Chevy Suburban and today on my way home I was stopped in traffic and every time I went to step on the gas it would not accelerate and in fact the tachometer and speed gauge would go down to 0. It would not accelerate. It was kind of like I was braking. When I lifted my foot of the accelerator it would go as it would if i had my foot off of it.

So I had to stop for a while with the car turned off and afterwards, it worked fine and got me home.

I also had put antifreeze in the reservoir the day before yesterday and noticed a antifreeze smell while driving. When I looked under the hood, the reservoir was dry today.

A problem that comes and goes might be the iac (idle air control) valve sticking. To clean the iac and throttle body bore and throttle plate, disconnect the large air intake tube, spray inside the throttle body with Carb/Throttle Body cleaner. To be sure that you’re getting the carbon deposits removed from the iac valve ports, remove the iac and spray the air passages in the throttle body, and the pintle of the iac.

Cant comment on your driveability concern,but it sounds like you need a cooling system pressure test the worst I can think of is a intake manifold leak.

The antifreeze smell could be coming from the heater core. Like oldschool said, the best way to find out where it’s leaking is with a pressure test of the cooling system.

Sorry, but I need to bump this to see if anyone knows what could be the problem. We did have the heater core replaced and still the problem accelerating is there. It only happens after the suburban has been running. Could it possibly be the transmission? We noticed that underneath the transmission is wet and there is a small leak, but the fluid lvl seems to be at normal level. Could it be the coolant which is also reddish color? The reservoir seems to be getting low very fast. Please if someone has any ideas. We also recently had the filter and pump replaced because it had gone out and recently replaced the EGR valve, because that was what the computer was showing was bad, but the engine light is still on. Thanks!!!

Could the coolant leak be causing this also? The temp gauge is also always where it usually is.

Thnx, we are gonna get the pressurized testing done also. We have also sprayed the with carb cleaner and it seems to work a little and then acts up again. We were also recommended to clean the MAF with carb cleaner. IS that a good idea?? we also had a tune up done…and the fuel regulator changed out.

My WAG is that one or both of your catalytic converters could be plugged, or starting to get plugged. Try these two ideas:

  1. Start the truck on level ground. Slooooowly accellerate til upt to 40-50-60 MPH. If it gets up there smoothly then perhaps faster accelleration and shuddering could point to the cats.
  2. Once the truck is shuddering, put the truck in neutral and try reving the engine to 3000 RPM
    and see if the shuddering/low power continues or stops. If it continues shuddering it rules out much of transmission causes. If it immediately revs up smoothly then maybe the transmission is a problem point.
    A good muffler shop can test the flow through the cats to confirm the problem.

Why did you conclude the acceleration problem was related to the heater core? Was the core leaking? I didnt like to do heater cores at all.

For the missing coolant when there is no visible sign: check for foamy brown colored oil under the oil filler cap.

His coolant loss issue is separate from the hesitation problem. At least that’s how I read it.

Thanks for all the feedback. Well, when I took it in and told the guy about the problem I had, he said it was the heater core. He said that if it wasn’t changed out that I would blow my engine, because the heater core helps cool the coolant. This is why I let him change the heater core out and also because I did have a leak from that area one time and our A/C is only blowing air…no cool air. I am not at all car wise and my husband is in and out at sea and works horrid hours.

OK another thing I forgot to add was that on the engine there appears to be salt like substance all over the alternator and in that area…I was told by my SIL that it could be the radiator leaking???

I will have my husband check and do all the recommendations and see what the results are.

No he writes “We did have the heater core replaced and still the problem accelerating is still there” How else could you read it? At times un-coding the OP is a battle,as Iam sure you all realize.

We checked this and there isn’t anything like that. However we now notice it leaking onto the ground. Its in the back area. Almost kind of like where it spilled out when the guy changes the heater core. Not sure though. Also like I said below…there is salt like substance on the alternator and in that area…a radiator leak maybe?? Gonna take it in to get that test done hopefully friday or this week end.

My husband said that if he accelerates very slowly it wont happen, its just accelerating at normal speed when it is hot. Also that on the number 2. The shuddering doesnt go away. It continues after he does this suggestion. I was also told that catalytic converters don’t go bad. Is this true??? Thanks a lot to all of you!!!

What did the mechanic say the problem with the heater core was? pluged up,leaking? Did he use the words DexCool? What I do know is people have been blocking off the coolant flow to their leaking heater cores for eons,without causing engine damage/overheating. Sorry to put you through all these questions.But things dont sound right. Do they salt the roads in your area? the residue you speak of could be last winters salt.I see from one of your posts you say coolant is red this is DexCool. Your coolant/driveability problems are not becoming one in my mind,but you are being told they are related.

What he said regarding the heater core was that it cools down the coolant or helps to cool it down. He said that if its old and stops working or is worn out which was probably what happened to ours , it won’t cool down the coolant and thus the coolant wont cool down the engine and not to drive it until the heater core was replaced. He then said that if I didn’t get it replaced…the engine would keep overheating and I would end up with a blown engine. He asked me if it was wet inside or if I noticed that there was any leaking on the inside of the car and i said it leaked once. It was after days of it being on (I had to travel a long ways) This is also when the A/C started to go out. But with the A/C he said to get it recharged, which we haven’t done and that it would work. Ours does require Dex Cool although I think we had used a while back the 50/50 that is supposed to be for all types. But we went back to Dex Cool, because we were told that the all other was not good for cars that require Dex Cool even though they said it was ok.

We have been in VA for a little over a year,first up north and now in the south and both places haven’t had snow while we were there and here. Its also a recent thing. I also noticed that the day the driveability problem had happened that it appeared that antifreeze sprayed from the radiator cap. The temp gauge also does not read hotter than normal. I hope this helps. I don’t mind the questions!! I just hope you don’t mind a person who doesn’t know much about cars!!

Well update. We did get the pressure test done and it turns out that the coolant leak is the Intake Valley Gasket.

Get your money back on that heater core unless they can show you it was leaking or plugged. Google DexCool settelment. Class action lawsuit settlement $50.00 to $800.00 for damage caused by DexCool in particular to intake manifold gaskets. Why is your mechanic not telling you this? There is a cutoff date so get on it.I looked the site over more carefully,doesnt look like it applies to your model and engine size,sorry look it over yourself.